Heck, who knows?
mcfly, VRB...what do you think you would have done?
I've never been in a situation quite like that, but I've been an early responder in a few car accidents (having spent way, way too much of the last decade on the road). I've always tried to be calm and helpful.
But the kind of person you really want at a scene like that is my wife. She's an RN and as such is legally obligated to help at an emergency scene (did you know that?). I've seen her "in action" twice, and both times she not only kept a level head but took charge, getting people out of harm's way, organizing others and caring for the injured. Her abilities in a bad situation go far beyond her medical training.