Active shooter situations are rare, but they have dramatically increased and become deadlier in recent years. These shootings occur in places such as churches, workplaces, theaters, schools, concert venues, and shopping malls. Learn steps for what to do if you find yourself in the same location as an active shooter. The Department of Homeland Security (DHS) defines an active shooter as a person in a populated and confined area who is actively engaged in killing or trying to kill people. The agency says these shooting incidents evolve quickly and are highly unpredictable.