All cell phones are 911 enabled, even those w/o a service plan. Keep that last year's model in the glove box, even if you can't make a normal call from it.
If BG no longer appears to be a threat to you or bystanders, order everyone back to cover and call 911 for an ambulance. Twelve of your peers may be trying to give you the benefit of the doubt, and that would give them something to sink their teeth into.
If you call 911, you are rendering aid. That would be the extent of it. I am not a doctor, and my emotions would be topsy turvey to say the least. If I get the authorities on the way, that is enough for me. If you remember the LA shoot out. They wounded the last perp then stood around a watched him die. Fine by me. No trial. They did get sued but it was thrown out of court. There was some comments about knowing if there was another threat so they were looking for that and staying under cover. Whatever, the results were good.
F'em if I had to shoot him he "needed shootin'" I'm not tending to his wounds and getting AIDS.