To quote Jeff Cooper:
AndThe police cannot protect the citizen at this stage of our development, and they cannot even protect themselves in many cases. It is up to the private citizen to protect himself and his family, and this is not only acceptable, but mandatory.
AndFight back! Whenever you are offered violence, fight back! The aggressor does not fear the law, so he must be taught to fear you. Whatever the risk, and at whatever the cost, fight back!
The only acceptable response to the threat of lethal violence is immediate and savage counterattack. If you resist, you just may get killed. If you don't resist you almost certainly will get killed. It is a tough choice, but there is only one right answer.