Check out my recent interview in an independent documentary regarding security and concealed carry of firearms on college campuses.  This is an obvious concern for security professionals trying to balance the benefits of a qualified armed response to an active shooter, versus the fear and misunderstanding some have about firearms.  If you have heard one of my lectures or attended one of our trainings then you will hear some familiar ideas.  Except for running out of bullets or committing suicide, the only thing stopping an active shooter is another shooter.  And in the world of self-defense, we don't use force because we can, we use force because we must."