Police are investigating a collision between a motorcycle and a car on Reid Highway

A motorbike rider is in hospital after a devastating collision with a car, which closed off Reid Highway last night.

Emergency services were called to the scene about 8.15pm after a white 4WD and a motorcycle collided at the intersection of West Swan Road.

It is understood an off-duty firefighter made the 000 call after coming across the crash on the busy highway.

The rider, a man in his 50s, was rushed to Royal Perth Hospital with serious injuries, while the driver of the car, a woman in her 50s was not injured.

She is assisting police with their enquiries and Major Crash detectives will investigate the crash further.