An air ambulance was called to a Doncaster park after a nearby car crash.
The helicopter landed in Sandall Park, off Barnby Dun Road, at about 6pm yesterday.
Police and a road ambulance were already at the scene of the crash.
Witnesses said the Yorkshire Air Ambulance helicopter eventually took off without picking anyone up, and the road ambulance drove away without its blue lights on.
Details of what happened have not yet been confirmed by police or the ambulance services.