The story as I heard it was this helicopter was located on the ramp between some hangers.
Two mechanics were working on this helicopter.
Each mechanic was positioned on each side standing outside on the landing skids.
The pilot controlling the helicopter was attempting to keep it stationary on the ground with the rotors turning.
This type helicopter can require a little more attention as the collective pitch can continue to increase
requiring the pilot to keep it in check or the helicopter will leave the ground.
Well it is rumored the collective pitch may have got away causing the helicopter to lift.
One mechanic said f that and as the helicopter became airborne he jumped and ran, the helicopter started a
sideways drift fortunately in the opposite direction of the scrambling mechanic.

The other mechanic held on for the ride, short ride.
The helicopter rotors obviously impacted the hanger.
When the helicopter came to rest everyone was alive.
The mechanic that held on ended up inside the helicopter, he did spend a couple days in the hospital.
The pilot ended up on the ground underneath the helicopter.
I'm pretty sure that's not him with the beer leaning on the hanger wall.

Again this is all second hand information.
No bystanders were seriously injured.