I'm glad no one was hurt, these things are inherently dangerous.

I was standing behind one once when a 3 1/2 inch plastic spinner and prop exploded, it was an APC prop and it hit the side of my house very hard, if it would have hit me it would have been a serious injury for sure.

Then another time I was walking from one side of a 60cc plane to the other side, I walked in front of the plane instead of behind it, just when I got to the other side before I got behind it again, the prop stirred up a small rock and the propeller hit it.  The rock hit my right thigh so hard it went through my jeans and into the meat of my leg, I pulled it out with a hemostat.  Ever been shot by a model airplane? Yep.