A mass shooting is an incident involving multiple victims of firearms-related violence. The United States' Congressional Research Service acknowledges that there is not a broadly accepted definition, and defines a "public mass shooting" as one in which four or more people selected indiscriminately, not including the perpetrator, are killed, echoing the FBI definition of the term "mass murder". However, according to the Investigative Assistance for Violent Crimes Act of 2012, signed into law in January 2013, a mass killing is defined as a killing with at least three deaths, excluding the perpetrator. Another unofficial definition of a mass shooting is an event involving the shooting (not necessarily resulting in death) of five or more people (sometimes four) with no cooling-off period.  Related terms include school shooting and massacre.
A mass shooting may be committed by individuals or organizations in public or non-public places. Terrorist groups in recent times have used the tactic of mass shootings to fulfill their political aims. Individuals who commit mass shootings may fall into any of a number of categories, including killers of family, of coworkers, of students, and of random strangers. Individuals' motives for shooting vary.
Responses to mass shootings take a variety of forms, depending on the context: number of casualties, the country, political climate, and other factors. The media cover mass shootings extensively, and, often, sensationally, and the effect of that coverage has been examined. Countries such as the United Kingdom and Australia have changed their gun laws in the wake of mass shootings. In contrast, the United States' constitution prohibits laws which disallow firearm ownership outright and owns about half of the world's guns.
The characterization of an event as a mass shooting depends upon definition and definitions vary. Under U.S. federal law the Attorney General may on a request from a state assist in investigating "mass killings", rather than mass shootings. The term was originally defined as the murder of four or more people with no cooling-off period but redefined by Congress in 2013 as being murder of three or more people. According to CNN, a mass shooting is defined as having four or more fatalities, not including gang killings or slayings that involve the death of multiple family members. In "Behind the Bloodshed", a report by USAToday, a mass killing is defined as any incident in which four or more were killed and also includes family killings. A crowdsourced data site cited by CNN, MSNBC, The New York Times, The Washington Post, The Economist, the BBC, etc., Mass Shooting Tracker, defines a mass shooting as any incident in which four or more people are shot, whether injured or killed. As of November 2017, the FBI defines a mass shooting as an incident involving "four or more people shot at once." A noteworthy connection has been reported in the U.S. between mass shootings and domestic or family violence, with a current or former intimate partner or family member killed in 76 of 133 cases (57%), and a perpetrator having previously been charged with domestic violence in 21. The lack of a single definition can lead to alarmism in the news media, with some reports conflating categories of crimes.
In Australia, a 2006 paper defined a mass shooting as "one in which ⩾5 firearm‐related homicides are committed by one or two perpetrators in proximate events in a civilian setting, not counting any perpetrators".
Crime violence research group Gun Violence Archive, whose research is used by all major American media outlets defines Mass Shooting as "FOUR or more shot and/or killed in a single event [incident], at the same general time and location not including the shooter" differentiating between Mass Shooting and Mass Murder [Killing] and not counting shooters as victims.
An act is typically defined as terrorist if it "appears to have been intended" to intimidate or to coerce people; a mass shooting is not, in itself, an act of terrorism. A U.S. congressional research service report explicitly excluded from its definition of public mass shootings those in which the violence is a means to an end, for example where the gunmen "pursue criminal profit or kill in the name of terrorist ideologies".
By continent and regionEdit
Mass shootings have occurred on the African continent, including the 2015 Sousse attacks, the 2015 Bamako hotel attack, the 2013 Westgate shopping mall attack in Nairobi, Kenya, and the 1994 Kampala wedding massacre. Most mass shootings in Africa have stemmed from terrorism, with tourists and diplomats frequently being the targets. Workplace violence and prejudice against ethnic minorities have less-frequently been involved in such spontaneous acts of mass violence.
The single deadliest event was the 2008 Mumbai attacks in which 164 people were killed and a further 308 people were wounded by terrorists.
South Korea has suffered multiple mass shootings in the South Korean Army, mainly due to soldier's stress and conflicts from its violence and detention from society.
Japan has as few as two gun-related homicides per year. These numbers include all homicides in the country, not just mass shootings.
There have been many mass shootings in Israel such as the 1972 Lod Airport Massacre, which killed 26 and injured 80, the 2002 Bat Mitzvah massacre and the June 2016, massacre at the popular Sarona center complex. These were all planned or executed by Palestinian or Arab terrorists.
In addition there have been two mass shootings by Jews in Israel. In 1991, Ami Popper was convicted of murdering seven Palestinian men in a mass shooting carried out in 1990. In 1994 Baruch Goldstein murdered 29 Muslims worshipping and injuring a further 125 in Hebron. Also known as the Cave of the Patriarchs massacre.
Several mass shootings have occurred in Europe, including the November 2015 Paris attacks, the 2012 Toulouse and Montauban shootings, the 2011 Norway attacks, the 2009 Winnenden school shooting, the 2007 Jokela school shooting, the 2008 Kauhajoki school shooting, the 2001 Zug massacre, the 2002 Erfurt massacre, the 1987 Hungerford massacre, the 1990 Puerto Hurraco massacre, the 1993 Greysteel massacre, the 2010 Cumbria shootings and the 1996 Dunblane massacre.
Notable mass shootings include the 1992 Tatarstan shooting, the 2002 Yaroslavsky shooting, the 2002 Moscow theater hostage crisis, the 2004 Beslan school siege, the 2012 Moscow shooting, the 2013 Belgorod shooting, and the 2014 Moscow school shooting.
Notable mass shootings in Canada include the 1989 École Polytechnique massacre, the 1992 Concordia University massacre, the 2012 Danzig Street shooting, the 2014 Edmonton killings and the 2017 Quebec City mosque shooting.
In one study by Adam Lankford, it has been estimated that 31% of public mass shootings occur in the U.S., although it has only 5% of the world's population. CNN cites a study by criminologist A. Lankford that finds that "there are more public mass shootings in the United States than in any other country in the world". The study concludes that "The United States and other nations with high firearm ownership rates may be particularly susceptible to future public mass shootings, even if they are relatively peaceful or mentally healthy according to other national indicators." Criminologist Gary Kleck criticized Adam's findings stating the study fails to provide evidence that gun ownership increases mass shootings and that Lankford has been unwilling to share a list of his cases, provide a list of the number of attacks per country, or even list his sources so that others can check his numbers. Mass shootings have also been observed to be followed by an increase in the purchase of weapons, but this phenomenon seems to be driven by a minority since neither gun owners nor non-owners report an increased feeling of needing guns.
Victims and survivorsEdit
After mass shootings, some survivors have written about their experiences and their experiences have been covered by journalists. A survivor of the Knoxville Unitarian Universalist church shooting wrote about his reaction to other mass shooting incidents. The father of a victim in a mass shooting at a movie theater in Aurora, Colorado, wrote about witnessing other mass shootings after the loss of his son. The survivors of the 2011 Norway attacks recounted their experience to GQ. In addition, one paper studied Swedish police officers' reactions to a mass shooting.
Notable mass shooters from outside the United States include Anders Behring Breivik (Norway, 2011), Robert Steinhauser and Tim Kretschmer (Germany, 2002 and 2009), William Unek (Africa, 1954 and 1957), Marc Lépine and Valery Fabrikant, (Canada, 1989 and 1992), Pekka-Eric Auvinen and Matti Juhani Saari (Finland, 2007 and 2008),Genildo Ferreira de França (Brazil, 1997), Friedrich Leibacher (Switzerland, 2001), Ľubomír Harman (Slovaskia, 2010), Tristan van der Vlis (Netherlands, 2011), Richard Komakech (Uganda, 1994), Omar Abdul Razeq Abdullah Rifai (Egypt, 2013), Farda Gadirov (Azerbaijan, 2009), Martin Bryant (Australia, 1996), Michael Robert Ryan and Derrick Bird (England, 1987 and 2010), Thomas Hamilton (Scotland, 1996) and Woo Bum-kon (South Korea, 1982).
Notable perpetrators of massacres in the U.S. include Edward Charles Allaway, James Edward Pough, Carl Robert Brown, Omar Mateen, Robert A. Hawkins, James Oliver Huberty, Nathan Dunlap, George Hennard, Dylann Roof, Adam Lanza, Nidal Malik Hasan, Charles Whitman, Jeff Weise, Gang Lu, Patrick Sherrill, Barry Loukaitis, Esteban Santiago, Christopher Harper-Mercer, Gian Luigi Ferri, Mark Essex, Scott Evans Dekraai, Steven Kazmierczak, Jennifer San Marco, James Eagan Holmes, Anthony F. Barbaro, Michael McLendon, Rodrick Shonte Dantzler, Jared Lee Loughner, Seung-Hui Cho, Elliot Rodger, Charles Carl Roberts IV, Rizwan Farook and Tashfeen Malik, Robert Lewis Dear, Mitchell Johnson and Andrew Golden, Aaron Alexis, Wade Michael Page, Eric Harris and Dylan Klebold, Patrick Edward Purdy, Gavin Eugene Long, Micah Xavier Johnson, Kyle Aaron Huff, One L. Goh, Stephen Paddock, Devin Patrick Kelley and Nikolas Cruz. U.S. mass shooters are overwhelmingly males. According to a database compiled by Mother Jones magazine, the race of the shooters is approximately proportionate to the overall U.S. population, although Asians are overrepresented and Latinos underrepresented. Criminologist James Allen Fox said that most mass murderers do not have a criminal record, or involuntary incarceration at a mental health center, but an article in the New York Times in December 2015 about 15 recent mass shootings found that six perpetrators had had run-ins with law enforcement, and six had mental health issues.
Mass shootings can be motivated by misanthropy and terrorism and caused by mental illness, inceldom and extensive bullying among other reasons. Forensic psychologist Stephen Ross says that extreme anger and the thought shooters are working for a cause, rather than mental illness, is most often the explanation. A study by Vanderbilt University researchers found that "fewer than 5% of the 120,000 gun-related killings in the United States between 2001 and 2010 were perpetrated by people diagnosed with mental illness". John Roman of the Urban Institute argues that, while better access to mental health care, restricting high powered weapons, and creating a defensive infrastructure to combat terrorism are constructive, they don't address the greater issue, which is "we have a lot of really angry young men in our country and in the world."
Author Dave Cullen described killer Eric Harris as an "injustice collector" in his 2009 book Columbine. He expanded on the concept in a 2015 New Republic essay on injustice collectors, identifying several notorious killers as fitting the category, including Christopher Dorner, Elliot Rodger, Vester Flanagan, and Andrew Kehoe. Likewise, mass shooting expert and former FBI profiler Mary O'Toole also uses the phrase "injustice collector" in characterizing motives of some mass shooting perpetrators. In relation, criminologist James Alan Fox contends that mass murderers are "enabled by social isolation" and typically experience "years of disappointment and failure that produce a mix of profound hopelessness and deep-seated resentment." Jillian Peterson, an assistant professor of criminology at Hamline University who is participating in the construction of a database on mass shooters, noted that two phenomena surface repeatedly in the statistics: hopelessness and a need for notoriety in life or in death. Notoriety was first suggested as a possible motive and researched by Justin Nutt. Nutt stated in a 2013 article, "those who feel nameless and as though no one will care or remember them when they are gone may feel doing something such as a school shooting will make sure they are remembered and listed in the history books." 
In considering the frequency of mass shootings in the United States, criminologist Peter Squires says that the individualistic culture in the United States puts the country at greater risk for mass shootings than other countries, noting that "many other countries where gun ownership is high, such as Norway, Finland, Switzerland and Israel . . . tend to have more tight-knit societies where a strong social bond supports people through crises, and mass killings are fewer." He is an advocate of gun control, but contends there is more to mass shootings than the prevalence of guns.
Social science and family structureEdit
According to Michael Cook and Carolyn Moynihan of Mercatornet, an angle that is missed by mainstream media is the findings of important social scientists such as eminent Harvard sociologist Robert J. Sampson who wrote: “Family structure is one of the strongest, if not the strongest, predictor of variations in urban violence across cities in the United States. The close empirical connection between family breakdown and crime suggests that increased spending on crime-fighting, imprisonment, and criminal justice in the United States over the last 40 years is largely the direct or indirect consequence of marital breakdown.” His views are echoed by the eminent criminologists Michael Gottfredson and Travis Hirschi, who have written that “such family measures as the percentage of the population divorced, the percentage of households headed by women, and the percentage of unattached individuals in the community are among the most powerful predictors of crime rates.”
Based on the research of another social scientist who was himself raised by a single mother, Bradford Wilcox, "boys living in single mother homes are almost twice as likely to end up delinquent compared to boys who enjoy good relationships with their father."
Moynihan said that "almost all school shooters come from families where the parents are either divorced or alienated", and Cook argued that "perhaps they wouldn’t need more gun control if they had better divorce control.”
This section needs expansion. You can help by adding to it. (November 2017)
Some people have considered whether media attention revolving around the perpetrators of mass shootings is a factor in sparking further incidents. In response to this, some in law enforcement have decided against naming mass shooting suspects in media-related events, in order to avoid giving them notoriety.
The effects of messages used in the coverage of mass shootings has been studied. Researchers studied the role the coverage plays in shaping attitudes toward persons with serious mental illness and public support for gun control policies.
Some news media have weighed in on the gun control debate. After the 2015 San Bernardino attack, the New York Daily News' front-page headline, "God isn't fixing this", was accompanied by "images of tweets from leading Republicans who shared their 'thoughts' and 'prayers' for the shooting victims".
Gun law reformEdit
Responses to mass shootings take a variety of forms, depending on the country and political climate.
After the 1996 Port Arthur massacre in Australia, the government changed gun laws in Australia. As in the United States, figures vary according to the definition of "mass shooting"; a 2006 paper used a definition "one in which ⩾5 firearm‐related homicides are committed by one or two perpetrators in proximate events in a civilian setting, not counting any perpetrators", compared to the usual U.S. definition of an indiscriminate rampage in public places resulting in four or more victims killed. Between 1981 and the passing of the law in 1996 there were 13 mass shootings with five or more deaths; in the following decade, while the new law was in place, there were no such mass shootings. Overall gun deaths have continued to decline for two decades since the law was passed.
There were four significant shootings, though not meeting the "mass shooting" definition of the 2006 paper, between 1996 and June 2016[update]:
- the Monash University shooting in 2002 in which Huan Yun Xiang shot and killed two and injured five
- the Hectorville Siege in 2011 where 39-year-old man Donato Anthony Corbo shot four people on a neighbouring property (three of whom died), and also wounded two police officers, before being arrested by Special Operations police after an eight-hour siege
- the Logan family shooting in 2014 of a neighbour family (Greg Holmes, 48, his mother Mary Lockhart, 75, and her husband Peter Lockhart, 78) by Ian Francis Jamieson
- the Hunt family murders which was also in 2014 when a farmer shot dead 4 family members then later killed himself.
As a result of the 1987 Hungerford massacre and 1996 Dunblane school massacre mass shootings, the United Kingdom enacted tough gun laws and a buyback program to remove guns from private ownership. There has been one mass shooting since the laws were restricted, the Cumbria shootings in 2010 which killed 13 people.
In the United States, support for gun law reform varies considerably by political party, with Democrats generally more supportive and Republicans generally more opposed. Some in the U.S. believe that tightening gun laws would prevent future mass shootings. Some politicians in the U.S. introduced legislation to reform the background check system for purchasing a gun. A vast majority of Americans support tighter background checks. "According to a poll [...] by Quinnipiac University in Connecticut, 93 percent of registered voters said they would support universal background checks for all gun buyers."
Others contend that mass shootings should not be the main focus in the gun law reform debate because these shootings account for less than one percent of the U.S. homicide rate and believe that these shootings are hard to stop. They often argue that civilians with concealed guns will be able to stop shootings.
Gun control policies may cause a lot of controversy due to divided opinions on who should be able to carry a weapon. An opinion survey was conducted by the firm GfK Knowledge Networks to differentiate between the different attitudes towards gun control. There was a gun policy survey and a mental illness survey. Studies showed that over 85% of those questioned supported national background checks into the mental health records of citizens attempting to purchase a gun. More than 50% of people felt that those suffering with mental health issues were more deviant and threatening than those who had good mental health. The study also proved that there is large interest in contributing to mental health awareness as well as simply prohibiting those suffering from purchasing guns. Nearly two thirds of respondents supported greater government spending on mental health, with more than 60% of people believing this would reduce gun violence in the USA. (Colleen L. Barry, 2013)
As of June 2016, U.S. President Barack Obama had spoken in the aftermath of fourteen mass shootings during his nearly eight-year presidency, repeatedly calling for more gun safety laws in the United States. After the Charleston church shooting, U.S. President Barack Obama said, "At some point, we as a country will have to reckon with the fact that this type of mass violence does not happen in other advanced countries. It doesn't happen in other places with this kind of frequency." After the December 2015 San Bernardino attack, Obama renewed his call for reforming gun-safety laws and also said that the frequency of mass shootings in the United States has "no parallel in the world". After the February 2018 attack at Florida's Parkland school shooting at Stoneman Douglas High School, the school's student survivors, teachers, and parents became strong leaders in the effort to ban assault weapon sales and easy accessibility to military weapons.
- Weiss, Jeffrey (December 6, 2015). "Mass shootings in the U.S. this year? 353 — or 4, depending on your definition". Dallas Morning News. Retrieved December 6, 2015.
- Bjelopera, Jerome P. (March 18, 2013). "Public Mass Shootings in the United States: Selected Implications for Federal Public Health and Safety Policy" (PDF). CRS Report for Congress. Congressional Research Service. Retrieved December 8, 2015. "There is no broadly agreed-to, specific conceptualization of this issue, so this report uses its own definition for public mass shootings."
- Follman, Mark. "What Exactly Is A Mass Shooting". Mother Jones. Retrieved August 9, 2015.
- Morton, Robert J. "Serial Murder". FBI Updates, Reports and Publications. Retrieved December 8, 2015.
- "H.R. 2076 (112th): Investigative Assistance for Violent Crimes Act of 2012". govtrack.us. United States Congress. Retrieved 20 February 2018.
(I)the term mass killings means 3 or more killings in a single incident;
- Greenberg, Jacobson & Valverde, Jon, Louis & Miriam (February 14, 2018). "What we know about mass shootings". Politifact. Tampa Bay Times. Retrieved 20 February 2018.
As noted above, there is no widely accepted definition of mass shootings. People use either broad or restrictive definitions of mass shootings to reinforce their stance on gun control. After the 2012 Sandy Hook school shooting, Congress defined "mass killings" as three or more homicides in a single incident. The definition was intended to clarify when the U.S. Attorney General could assist state and local authorities in investigations of violent acts and shootings in places of public use.
- Ingraham, Christopher (3 December 2015). "What makes a 'mass shooting' in America". Washington Post. Retrieved 5 November 2017.
But starting in 2013, federal statutes defined "mass killing" as three or more people killed, regardless of weapons.
- Follman, Mark. "What Exactly Is A Mass Shooting". Mother Jones. Retrieved August 9, 2015.
In January 2013, a mandate for federal investigation of mass shootings authorized by President Barack Obama lowered that baseline to three or more victims killed.
- "Report: U.S. averages nearly one mass shooting per day so far in 2017". Retrieved 15 February 2018.
- "About the Mass Shooting Tracker". Mass Shooting Tracker. Retrieved 13 June 2016.
- team, Guardian US interactive; Morris, Sam; team, Guardian US interactive; Morris, Sam. "1,516 mass shootings in 1,735 days: America's gun crisis – in one chart". Retrieved 15 February 2018 – via www.theguardian.com.
- Fisher, Max; Keller, Josh (7 November 2017). "What Explains U.S. Mass Shootings? International Comparisons Suggest an Answer". Retrieved 15 February 2018 – via NYTimes.com.
- CNN, Kara Fox, CNN Graphics by Henrik Pettersson,. "America's gun culture vs. the world in 5 charts". Retrieved 15 February 2018.
- Follman, Mark (December 3, 2015). "How Many Mass Shootings Are There, Really?". New York Times. Retrieved December 6, 2015.
- "PUBLIC LAW 112–265" (PDF). United States Congress. January 14, 2013. Retrieved December 6, 2015.
- Christensen, Jen (August 28, 2015). "Why the U.S. has the most mass shootings". CNN.
- "Behind the Bloodshed". USA Today. Retrieved December 3, 2015.
- "Orlando club shootings: Full fury of gun battle emerges". - BBC News. 13 June 2016. Retrieved 13 June 2016. Cites Mass Shooting Tracker
- "Are Americans becoming "numb" to mass shootings?". Retrieved 15 February 2018.
- Melissa Jeltsen (18 July 2014). "Mass Shooting Analysis Finds Strong Domestic Violence Connection". The Huffington Post. Retrieved 13 June 2016.
- "Analysis of Mass Shootings". Everytownresearch.org. 20 August 2015. Retrieved 13 June 2016. This analysis has later figures than reported in the article
- Mark Follman (December 18, 2015). "No, There Has Not Been a Mass Shooting Every Day This Year". Mother Jones.
- Chapman, S. (December 2006). "Australia's 1996 gun law reforms: faster falls in firearm deaths, firearm suicides, and a decade without mass shootings". Injury Prevention. 12: 365–72. doi:10.1136/ip.2006.013714. PMC . PMID 17170183.
- "General Methodology - Gun Violence Archive". www.gunviolencearchive.org.
- Ana Swanson (3 December 2015). "When should a shooting really be called 'terrorism'?". The Washington Post. Retrieved 27 June 2016.
- Fisher, Max (July 23, 2012). "A Land Without Guns: How Japan Has Virtually Eliminated Shooting Deaths". The Atlantic. Retrieved December 16, 2015.
- "US Mass Shootings, 1982-2018: Data From Mother Jones' Investigation".
- U.S. Leads World in Mass Shootings. The Wall Street Journal. Retrieved: October 2, 2017.
- Why the US has the most mass shootings. CNN. Retrieved: October 2, 2017.
- Why the U.S. is No. 1 -- in mass shootings. Los Angeles Times. Retrieved: October 2, 2017.
- The United States Has Had More Mass Shootings Than Any Other Country. Mother Jones. Retrieved: October 2, 2017.
- Lott, John (July 31, 2016). "We adjust for population with murder rates. Why not for mass shootings?". Los Angeles Times.
- Lott, John (January 7, 2016). "UPDATED: Comparing Death Rates from Mass Public Shootings and Mass Public Violence in the US and Europe". Crime Prevention Research Center.
- Why the U.S. Has 31% of the World's Mass Shootings. TIME. Retrieved: October 2, 2017.
- Lankford, Adam (2016). "Public Mass Shooters and Firearms: A Cross-National Study of 171 Countries". Violence and Victims. 31 (2): 187–199. doi:10.1891/0886-6708.VV-D-15-00093. ISSN 0886-6708. (subscription required)
- Lott, Maxim (28 July 2016). "Critics shoot holes in widely cited gun study".
- Stroebe, Wolfgang; Leander, N. Pontus; Kruglanski, Arie W. (2017-08-11). "The impact of the Orlando mass shooting on fear of victimization and gun-purchasing intentions: Not what one might expect". PLOS ONE. 12 (8): e0182408. doi:10.1371/journal.pone.0182408. ISSN 1932-6203.
- "Port Arthur massacre (Australia)". Wikipedia. 2018-03-03.
- Follman, Mark (July 27, 2012). "'I Was a Survivor': Recalling a Mass Shooting 4 Years Ago Today". Mother Jones. Retrieved August 11, 2015.
- Teves, Tom (July 31, 2015). "'Something is very wrong in our society': Father of mass-shooting victim calls for an end to the carnage". Salon. Retrieved August 12, 2015.
- Flynn, Sean (July 30, 2012). "Is he coming? Is he? Oh God, I think he is". GQ. Retrieved August 12, 2015.
- Karlsson, Ingemar. "Memories of traumatic events among swedish police officers". Stockholm University. Retrieved August 11, 2015.
- Simmons, Laura (June 29, 2014). "Post Traumatic Stress Disorder in Mass Shooting Survivors". Liberty Voice. Retrieved August 11, 2015.
- "Impact of Mass Shootings on Individual Adjustment" (PDF). ptsd.va.gov. National Center for PTSD. Retrieved August 11, 2015.
- Frum, David (June 23, 2015). "Mass Shootings Are Preventable". The Atlantic. Retrieved August 11, 2015.
- Kluger, Jeffrey (May 25, 2014). "Why Mass Killers Are Always Male". Time. Retrieved August 11, 2015.
- Ford, Dana (July 24, 2015). "Who commits mass shootings?". CNN.
- Peters, Justin (2013-12-19). "Mass shootings in America: Northeastern criminologists James Alan Fox, Monica J. DeLateur in Homicide Studies refute common myths about mass murder". Slate.com. Retrieved 2016-07-08.
- Buchanan, Larry (December 3, 2015). "How They Got Their Guns". New York Times. Retrieved June 12, 2016.
- De Freitas, Julian, and Mina Cikara. "Deep down my enemy is good: Thinking about the true self reduces intergroup bias." (2017)
- Van Brunt, Brian, and W. Scott Lewis. "Costuming, misogyny, and objectification as risk factors in targeted violence." Violence and gender 1.1 (2014): 25-35.
- Rocque, Michael. "Exploring school rampage shootings: Research, theory, and policy." The Social Science Journal 49.3 (2012): 304-313.
- Campbell, Holly (December 2, 2015). "Inside the mind of a mass murderer". WANE.com. Retrieved December 10, 2015.
- Wolf, Amy (December 11, 2014). "Mental Illness is the wrong scapegoat after mass shootings". Vanderbilt University. Retrieved August 12, 2015.
- Angry young Men and Mass Killings. The Huffington Post. June 16, 2016.
- "Finally understand why. Dave Cullen's Edgar-winning Columbine book: the Columbine killers, shooting & myths". davecullen.com. Retrieved September 27, 2015.
- Cullen, Dave (August 31, 2015). "Inside the Warped Mind of Vester Flanagan and Other Shooters". The New Republic. Retrieved September 27, 2015.
- Bekiempis, Victoria (September 4, 2015). "Meet Mass-Shooting Expert Mary Ellen O'Toole". Newsweek. Retrieved September 6, 2015.
- Fox, James Alan (January 16, 2011). "The real causes of mass murder". Boston.com. Retrieved November 25, 2015.
- "James Alan Fox: In San Bernardino, focus on the murderous partnership". USA Today. December 3, 2015.
- Wanamaker, John (October 8, 2017). "'This shooter is a little different': Hamline professor studies mass shootings". MPR News. Retrieved October 9, 2017.
- "School Shootings and Possible Causes". 14 December 2013. Retrieved 15 February 2018.
- Dorell, Oren (December 18, 2012). "In Europe, fewer mass killings due to culture not guns". USA Today. Retrieved August 11, 2015.
- Birch, Jenna (July 27, 2015). "Does Media Coverage After a Mass Shooting Do More Harm Than Good?". Yahoo! News. Retrieved August 11, 2015.
- Elinson, Zusha; Lazo, Alejandro (October 4, 2015). "More Police Decide Against Naming Mass-Shooting Suspects". Wall Street Journal. Retrieved October 5, 2015.
- McGinty, Emma (2013). "Effects of News Media Messages About Mass Shootings on Attitudes Toward Persons With Serious Mental Illness and Public Support for Gun Control Policies". American Journal of Psychiatry. American Psychiatric Association. 170 (5): 494–501. doi:10.1176/appi.ajp.2013.13010014. PMID 23511486. Retrieved August 11, 2015.
- Colin Campbell (December 2, 2015). "Hard-hitting Daily News cover blasts Republicans for offering only 'prayers' after latest shooting". Business Insider. Retrieved December 3, 2015.
- Fang, Marina (December 2, 2015). "New York Daily News Skewers Politicians Refusing to Act on Gun Violence: 'God Isn't Fixing This'". Huffington Post. Retrieved December 2, 2015.
- Dewan, Angela; Tarabay, Jamie (6 December 2017). "What the UK and Australia did differently after mass shootings". CNN. Retrieved 31 January 2018.
- Grimson, Matthew (October 2, 2015). "Port Arthur Massacre: The Shooting Spree That Changed Australia's Gun Laws". NBC News. Retrieved October 3, 2015.
- Hartmann, Margaret (October 2, 2015). "How Australia and Britain Tackled Gun Violence". Daily Intelligencer. Retrieved October 3, 2015.
- Collins, Sam (July 28, 2015). "One Change To Our Gun Laws That Could Have Prevented The Last Mass Shooting". Think Progress. Retrieved August 12, 2015.
- Weinberg, Ali (October 2, 2015). "These 6 Stalled Bills Aimed at Mass Shootings Like Umpqua Flounder in Congress". ABC News. Retrieved October 3, 2015.
- Andrews, Becca (October 1, 2015). "An Overwhelming Majority of Americans Still Support Universal Background Checks". Mother Jones. Retrieved December 16, 2015.
- Volokh, Eugene (October 3, 2015). "Do civilians with guns ever stop mass shootings?". Washington Post. Retrieved October 5, 2015.
- Korte, Gregory (October 2, 2015). "11 mass shootings, 11 speeches: How Obama has responded". USA Today. Retrieved October 3, 2015.
- Benen, Steve (June 23, 2015). "Comparing U.S. mass shootings to the rest of the world". MSNBC. Retrieved August 11, 2015.
- Tani, Maxwell (December 2, 2015). "OBAMA: 'We have a pattern now of mass shootings ... that has no parallel'". Business Insider. Retrieved December 16, 2015.
- Witt, Emily (19 February 2018). "How the Survivors of Parkland Began the Never Again Movement". The New Yorker. Retrieved 20 February 2018.
- Timeline: Deadliest U.S. mass shootings
- Public Mass Shootings in the United States: Selected Policy Implications Congressional Research Service
- Algoworld: Scientific Ways To Predict Mass Shootings
- Washington Case Revives Debate About 'Contagious' Mass Shootings
- Yes, Mass Shootings Are Occurring More Often. Mother Jones. October 21, 2014.