Uh... I once caught a kid who was about to fall from a second story balcony. Not sure if the fall would have been high enough to kill her, but it would have been nasty. She was going over backwards, so I guess she would have either landed on her head or turned right over and landed on her front.
I don't know what she thought she was doing sitting on the edge and I don't know why nobody told her to get down, but there she was. I was sitting nearby reading. I glanced up for no particular reason and noticed that she was kinda off balance. I remember thinking, "Hang on, is she about to fall? Nah, she's fine, stop being such a worryooOOHH FUCK ME DEAD SHE'S GOING OVER!" Leapt up faster than I would have thought possible, dashed over and grabbed her ankles.
The kid was really calm about the whole thing. She was only about five years old and she just sorta took it in stride. After I pulled her up she gave me a funny look like, "Why are you hold my ankles? I barely know you", then just wandered off. I was more shaken than she was.