KnowraActive shooterLinked fromLinked fromThe 4 pages that link to Active shooter, each with the reason it gives.All 4Related 4Mass murderRelated: This operational category guides immediate responses during some mass-murder incidents.Mass shootingRelated: This operational category often guides immediate response, but does not cover every mass shooting.School shootingRelated: This operational category guides immediate response during some school shootings.Charles WhitmanRelated: The attack exposed the difficulty of stopping a shooter firing from an elevated position.