No one was seriously hurt, and no police report got filed, which meant that I was free to go. An hour late. Sigh. I gave both men my card and went on my merry way.
So the real question is whether I had any obligation to stop. I did see what happened. And I was concerned that someone might be hurt. But aside from the obvious moral answer, what is the legal answer? Am I legally obligated to stop if I witness an accident? What if it's only a fender bender?
Anyway, I'm not sorry I stopped, but I'm curious anyway.