4) If, on my way to safety, I saw the bad guy as he was in the very act of killing innocent others -- which means and if, only if, I could see and clearly identify that he was in fact the bad guy, and not a plainclothes or off-duty officer or a good citizen who was shooting the real bad guy -- and if I reasonably believed I could take that shot without endangering others (more than they were already in danger) then I would take the shot. Otherwise, I would not.
That strikes me as a lot of thinking and evaluating, which takes precious time under such conditions. I am not as gracious as pax. I am looking to get myself out of there, or in hiding, just as quickly as I can. I like the thought of getting in ones car and making tracks.