Active shooter or active killer describes the perpetrator of a type of mass murder marked by rapidity, scale, randomness, and often suicide, usually associated with the United States. The United States Department of Homeland Security defines an active shooter as "an individual actively engaged in killing or attempting to kill people in a confined and populated area; in most cases, active shooters use firearms and there is no pattern or method to their selection of victims." Most incidents occur at locations in which the killers find little impediment in pressing their attack. Locations are generally described as soft targets, that is, they carry limited security measures to protect members of the public. In most instances, shooters commit suicide, are shot by police, or surrender when confrontation with responding law enforcement becomes unavoidable, and active shooter events are often over in 10 to 15 minutes. According to New York City Police Department (NYPD) statistics, 46 percent of active shooter incidents are ended by the application of force by police or security, 40 percent end in the shooter's suicide, 14 percent of the time the shooter surrenders and, in less than 1 percent of cases, the violence ends with the attacker fleeing.
Active shooter or active killer describes the perpetrator of a type of mass murder marked by rapidity, scale, randomness, and often suicide, usually associated with the United States. The United States Department of Homeland Security defines an active shooter as "an individual actively engaged in killing or attempting to kill people in a confined and populated area; in most cases, active shooters use firearms and there is no pattern or method to their selection of victims."