Seemed to work for these people and hell most of them probably weren't officially trained.
Pearl High School, Mississippi, 1997: After shooting several people at his high school, student heads for the junior high school; assistant principal Joel Myrick retrieves a .45 pistol from his car and points it at the gunman’s head, ending the murder spree. Total dead: Two.
Appalachian School of Law, 2002: Crazed immigrant shoots the dean and a professor, then begins shooting students; as he goes for more ammunition, two armed students point their guns at him, allowing a third to tackle him. Total dead: Three.
Edinboro, Pa., 1998: A student shoots up a junior high school dance being held at a restaurant; restaurant owner pulls out his shotgun and stops the gunman. Total dead: One.