You are the driver of a van, unarmed and untrained in these things, minding your own business as you roll to a stop at an intersection. Suddenly, a man appears at the door of your van, armed with a gun. Unknown to you, though you'll find out later, he is attempting to carjack you and has just shot another helpless, innocent victim in the center of the forehead and left him for dead. Suddenly, someone shouts at the armed offender, and he turns and raises his gun to shoot that person. The person who shouted fires his own gun, dropping the offender and also unintentionally wounding you. His actions have physically harmed you, but he has also saved you from probably being kidnapped by a man who shoots his victims in the forehead.