Mass shooting

A mass shooting is a violent crime in which one or more attackers use a firearm to kill or injure multiple individuals in rapid succession. There is no widely accepted specific definition, and different organizations tracking such incidents use different criteria. Mass shootings are characterized by the targeting (sometimes indiscriminate) of victims in a non-combat setting, and thus the term generally excludes gang violence, shootouts and warfare. The perpetrator of an ongoing mass shooting may be referred to as an active shooter.

Mass shootings may be done for personal or psychological reasons, such as by individuals who are deeply disgruntled, seeking notoriety, or are intensely angry at a perceived grievance; though they have also been used as a terrorist tactic, such as when members of an ethnic or religious group are deliberately targeted. It has been theorized that media coverage of mass shootings has contributed to some shooters who are motivated by fame-seeking. After mass shootings, mental health issues such as survivor's guilt and post-traumatic stress disorder are commonly suffered by survivors, first responders, and victims' loved ones.

The number of people killed in mass shootings is difficult to determine due to the lack of a commonly agreed upon definition. In the United States—the country with the most mass shootings—there were 103 deaths in mass shootings in 2021 (excluding the perpetrators) using the FBI's definition, and 706 deaths using the Gun Violence Archive's definition. Mass shootings are relatively rare in China, Singapore, South Korea, Japan, the United Kingdom, Russia, and across Africa.

Like other forms of gun violence, but particularly due to their higher casualty counts, mass shootings often prompt scrutiny of and changes to local firearms regulation. For example, the Dunblane massacre, Port Arthur massacre and Christchurch mosque shootings contributed to significant expansions of gun control restrictions in the United Kingdom, Australia and New Zealand.