Just this afternoon while running some trails outside of Harrisburg I heard a crack right before a tree branch dropped beside me. Not in front of, not behind, but eight feet to my right. It wasn't a large branch. I couldn't imagine being killed by it. But getting knocked out or at least bruised and bloodied seemed likely. To those that say that she would have been able to move out of way if she wasn't listening to music, I say no way. By the time the sound registers you are to close to react. Nor are you likely to even know which way to move to stay safe. Any branch large enough to be able to kill is probably large enough to hit you even if you step left, right, or try and stop.
Had she started her run ten seconds earlier, or paused at some point to adjust her shoelace, the branch would have missed her and none of us would know.
Life (and death) turn on amazing probabilities.