"Sue is shooting a soap box derby event when a firetruck crashes through the crowd, crushing a small child
Does Sue 1) photograph the dead child 2) photograph the truck 3) drop her camera to assist?"
Hypotheticals mean little. I'll give you an example: there's an annual event here where the folks go to the Formentor peninsula, chop down the straightest, tallest pine they can spot, get it into the sea and then tow it across the bay to the Port of Pollensa. The intention is to erect it in the square, shaved, and have people attempt to reach the top. One year, my wife and I were watching the trunk being taken from the beach, through a gap in the low wall separating beach from the pedestrianised walk area (disaster, but that's something else). There was the usual crush of watching crowd, kids at the front, excited parents behind them.
As the log itself was about to be dragged through the gap, the rope attached to it and being tugged by the team on the walkway, was running across the vertical edge of the low wall and at an angle of about sixty degrees. As the team stopped pulling, the rope went slack, and a child put its body up against that edge to get a better view, just as the rope was being taken up and tightened again. I stood there, frozen, watching a disaster about to unfold, a child crushed to death between a wall and a heavy rope. Fortunately, others were more reactive and screamed at the haulers to stop, and the kid was safe. That they could make their warning cries heard above the din of cheering was a minor miracle of its own.
Moral: if your Sue had my reactions, she'd do none of your suggested alternatives. There lies the folly of unreal situation planning. I'd always thought myself pretty quick to react to things. I was wrong.