Believe it or not I was actually present when a simlar incident happend at a mineral sands processing plant about 90 km north of Perth in the late eighties. The bases for a large kiln were being poured and I was chatting to the concrete truck driver who was operating the discharge lever on his truck. The next thing the guy started screaming and swearing clutching his hand hopping around like a mad man. When we finally got him calm enough to see what was causing the problem he showed us his hand which which was badly bruised and swelling up at an alarming rate. Something had hit him very hard between the thumb and forefinger, I remember looking around and there was only empty padocks as far as you could see and not a thing in the sky
. The only thing I could think of was something fell from space or some fool had randomly discharged a gun into the air. In any case we never found out what hit him but the damage to his hand was a lot worse then the kid in the pic below.
Mark