I'd probably barricade with my rig THEN get closer. Rubberneckers are going to be an issue, I'd want to have a "lee" behind my vehicle big enough for a rig to get into.

And while doing triage, if anyone is coherent, try to get them to stay in their seats, and if there are enough people that they are getting in the way, some start taking history.

As soon as the cavalry shows up, hand off and ask their boss where they want me, and if the answer is the hell off their scene I leave my name and contacts and get the hell off their scene.