A "mass shooting" is an incident involving multiple victims of firearm violence. There is no widely accepted definition of the term "mass shooting" but the FBI defines a "mass murder" as "four or more murdered during an event with no "cooling-off period" between the murders."
Different media outlets and research groups use different definitions for the term "mass shooting" For example , Crime violence research group "Gun Violence Archive" defines a "mass shooting" as " FOUR or more shot (injured 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 and not counting shooters as victims.