Mass shooting

A mass shooting is a violent crime in which one or more attackers kill or injure multiple individuals simultaneously using a firearm. There is no widely accepted definition of "mass shooting" and different organizations tracking such incidents use different definitions. Definitions of mass shootings exclude warfare and sometimes exclude instances of gang violence, armed robberies, familicides and terrorism. The perpetrator of an ongoing mass shooting may be referred to as an active shooter.

Mass shootings are most common in the United States. For more information, see this page: Mass shootings in the United States.