I'm not aware of any actual collisions. There could have been. I am aware of one drone that was a very large one, the size of a 737, which the U.S. Air Force was testing. They lost radio control, and it crashed very close to a neighbourhood. I think it was somewhere in California. That was a number of years ago. I am not aware of any actual collisions with aircraft.
On November 22nd, 2016. See this statement in context.