Mass shooting

A mass shooting is an incident involving multiple victims of gun 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. The lack of a single definition can lead to alarmism in the news media, with some reports conflating categories of crimes.

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. Countries such as Australia and the United Kingdom have changed their gun laws in the wake of mass shootings. The news media and other types of media cover mass shootings extensively, and the effect of that coverage has been examined.

The characterization of an event as a mass shooting depends upon definition and definitions vary. Under US 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 US 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.

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