Looking at the question in the headline, I don't think that the answer is necessarily cut and dry. If you happened to witness an accident (but weren't involved), there are valid reasons for both stopping and not stopping.
Yesterday was the first day of camp for my 6 year old love bug. And yep you guessed it, she got a splinter in the picnic table. Geeeeeeeeeez...drama! As I laugh, but really feel anxious knowing she's not going to let me get it out.