A friend of mine is a professional photojournalist. They know to just keep shooting when crazy shit happens.

I can't think of the names of the photographers involved, but some have attacked photojournalists on moral grounds when the photogs chose to snap pictures instead of actively help someone in need. The two cases I'm thinking of are the picture of the starving African child and the vulture, and the photos of a woman being swept out to sea and drowned when the photographer was in the best position to save her.

I think that when your job is capture images of dramatic or violent events, your first instinct when anything interesting happens is to shoot pictures.