A rescue helicopter has landed on the Hume Motorway at Pheasants Nest, where a man's arm has been amputated in a road accident.
Initial reports indicate the man, a motorcyclist aged about 50, collided at high speed with a car in the southbound lanes shortly after 2pm Saturday.
A NSW Ambulance spokeswoman said paramedics were dealing with “a critical right arm injury”.
The Mercury understands the injured man has passed in and out of consciousness and a tourniquet has been applied to the affected limb.
The collision occurred between the Pheasants Nest and Picton Road exits.
An elderly woman believed to have been at the wheel of the car is being assessed by paramedics.
A chopper landed about 50 metres south of the crash site, a short time ago.
Southbound lanes of the motorway are closed, with traffic diverted at Picton Road.