The Federal Bureau of Investigation (FBI) designated 61 shootings in 2021 as active shooter incidents. The FBI defines an active shooter as one or more individuals actively engaged in killing or attempting to kill people in a populated area. Implicit in this definition is the shooter’s use of a firearm. The active aspect of the definition implies the ongoing nature of an incident and thus the potential for the response to affect the outcome.
When evaluating shooting incidents to determine if they meet the FBI’s active shooter definitions, researchers considered for inclusion: