One question for all those who advocate warning shots:
From Wikipedia: "On the ground, a warning shot from a pistol, rifle, or shotgun is fired into the air, or occasionally into a nearby object, or aimed so that the shot passes the one being warned harmlessly. This is a sufficiently aggressive act to demand attention, and alert onlookers that they might be shot if directions are not followed."
Who is responsible for the round (warning shot) when it kills or seriously injures another completely oblivious person?
Answer: Whoever pulled the trigger (you).
Are you willing to except that responsibility to scare someone? If it warrants shooting a gun, shoot the threat. If it doesn't, hit the panic alarm on your car/home/etc., blow a whistle, scream, etc.
Or if you are dealing with someone in the military or law enforcement - just yell "Cease Fire."