Plane crashes onto San Diego highway killing passenger in parked car

Pilot fighting for his life in hospital after 'nerve-wracking' crash-landing

A light aircraft crashed onto a highway just outside San Diego and slammed into the back of a parked car, killing one woman and injuring five others.

Carrying two people, the single-engine Lancair IV made an emergency landing on Interstate 15 in Fallbrook, California.

The plane came down on its belly and skidded for more than 30 metres before it crashed into the Nissan car, which was parked on the side of the highway, said North County Fire Protection District spokesman John Buchanan.

The stationary Nissan which the plane crashed into the back of, killing one passenger. (AP)

The four people in the car had stopped to sync the sedan's Bluetooth wireless system, Mr Buchanan said. The woman who died had been sitting in the car's back seat.

Truck driver Bill Senclare told San Diego television station KGTV: "It was pretty nerve-wracking seeing the plane coming right over top of me and then hit the road and then slide up here and then hit that car."

The plane's pilot, a man in his 60s, was being treated in hospital with life-threatening injuries.

The passenger of the plane and three of the car's occupants were hospitalised with non-life threatening injuries.

It was not clear what caused the plane to come down on the highway.

The National Transportation Safety Bureau and the Federal Aviation Administration were investigating the causes of the crash.