Thanks for the responses. Unfortunately, in this scenario there is no one with more experience until a second responder arrives; the solo responder is on his/her own until help arrives. But your point is well taken; in my quest to do no harm, securing the scene -- setting out my LED road flares and calling 9-1-1 would be the top priorities, followed by whatever the operator asks. They'll probably want to know status of the victims which I can do. I'm quite comfortable with DP and serious bleeding injuries, but I'm not moving anybody who's strapped into a car. I do have extra nitrile gloves and more than a few 5x9's.

My FA training dates to my active duty days and since I've never worked anything other than a friend's hand injury (cut to the bone but not life threatening), I'm a tad rusty. I may talk with my fireman neighbor and see what he recommends re local training; the topic has never come up.