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". Another unofficial definition of a mass shooting is an event involving the shooting (not necessarily resulting in death) of four or more people 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 and political climate, among other factors. The news media and other types of media cover mass shootings extensively, and, often, sensationally, and the effect of that coverage has been examined. Countries such as Australia and the United Kingdom have changed their gun laws in the wake of mass shootings. In contrast, the United States' constitution currently prohibits laws which disallow firearm ownership outright.
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. 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".
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 frequent 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 several shootings such as the Bat Mitzvah massacre in Israel.
In 1991, Ami Popper was convicted of murdering seven Palestinian men in a mass shooting carried out in 1990.
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 and the 2010 Cumbria shootings.
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, 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. 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.
The frequency in which mass shootings occur depends upon definition. In "Behind the Bloodshed", a report by USA Today, said that there were mass killings every two weeks and that public mass killings account for 1 in 6 of all mass killings (26 killings annually would thus be equivalent to 26/6, 4 to 5, public killings per year).Mother Jones listed seven mass shootings, defined as indiscriminate rampages in public places resulting in four or more victims killed, in the U.S. for 2015. The average for the period 2011-2015 was about 5 a year. An analysis by Michael Bloomberg's gun violence prevention group, Everytown for Gun Safety, identified 110 mass shootings, defined as shootings in which at least four people were murdered with a firearm, between January 2009 and July 2014; at least 57% were related to domestic or family violence. This would imply that not more than 43% of 110 shootings in 5.5 years were non-domestic, though not necessarily public or indiscriminate; this equates to 8.6 per year, broadly in line with the other figures.
Other media outlets have reported that hundreds of mass shootings take place in the United States in a single calendar year, citing a crowd-funded website known as Shooting Tracker which defines a mass shooting as having four or more people injured or killed. In December 2015, The Washington Post reported that there had been 355 mass shootings in the United States so far that year. In August 2015, The Washington Post reported that the United States was averaging one mass shooting per day. An earlier report had indicated that in 2015 alone, there had been 294 mass shootings that killed or injured 1,464 people. However, an article from RT stated that 42 percent of the incidents involved zero deaths, and 29 percent one death. Shooting Tracker and Mass Shooting Tracker, sites that the media have been citing, have been criticized for using a criterion much more inclusive than that used by the government--they count four victims injured as a mass shooting--thus producing much higher figures.
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), Tim Kretschmer (Germany, 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), 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, Michael McLendon, 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, Eric Harris and Dylan Klebold, Patrick Edward Purdy, Gavin Eugene Long, Micah Xavier Johnson, Kyle Aaron Huff, One L. Goh and Stephen Paddock. 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, 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.
In considering the frequency of mass shootings in the United States, criminologist and gun-control advocate 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, however, tend to have more tight-knit societies where a strong social bond supports people through crises, and mass killings are fewer."
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 media publications 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".
Responses to mass shootings take a variety of forms, depending on the country and political climate.
After the 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 victims; in the 10.5 years between the passing of the law and the publication of the paper there were no such mass shootings. There were four significant shootings, though not meeting the "mass shooting" definition of the 2006 paper, between 1996 and June 2016 : 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 and 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.
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.
As of June 2016, U.S. President Barack Obama had given speeches on fourteen different mass shootings during his 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".