Only Leo gets to decide who is dangerous and needs shooting. Getting charged and having someone fighting over your gun is no excuse to shoot someone - if the person attacking is black, unless you are a Leo. No way would they take your gun and shoot you with it.
Sir: If I am headed down the public street on foot unarmed and you head me off twice with a truck and I have no private or public property close by to take refuge in and you obviously not an officer get out with a gun to attempt a hostile action on me am I doing anything unlawful if I try to take control of your firearm?