Hate to say it, but the moment the domestic broke out next to you, it was your duty to get that truck out of there, not be a hero. When I was trained, the truck is priority. No matter what happens, you get the truck out of harms way and call the cops later. Domestic breaking out could very well be a great distraction to get your attention away from anyone coming up behind you with weapons. Something like that happens, you gotta go. Thats the kind of thing my partner did before I got him, he was in the truck and his partner got involved in a domestic, next thing you know their being pulled to the ground at gun point and the truck is leaving without them in it.
Thanks for quarterbacking after the fact but the only thing I said was "Do I need to call the Police?" If that qualifies as being a hero then I guess I'm guilty. It was a three man crew involved in training and my partner was out standing back to back with me in a ready position.