This sadly is not an uncommon event, well maybe resulting in a death is but these toy heli's are lethal weapons. Much like an unguarded circular saw blade.
I've broken the tips of 3 fingers on one hand destroying the finger nails when my toy heli drifted into me whilst I was briefly looking down at the TX, I took my eyes off the machine for a nano second & the wind did the rest.
These UAV's or whatever the latest craze name is are now everywhere, R/C outlets are stocked to the roof with toy quad copters etc some with amazing features.
Gravity, as soon as they neutralize that then heaven 'elp us!
Wmk2