WA gunman demands bikes, shoots car

West Australian police are hunting for two men who allegedly stole off-road bikes while threatening the owners with a gun, then fired a shot into their car's engine.

The two male victims, aged 22 and 24, were approached by the men when they returned to the car, which was parked at the end of a dirt track in the Mandurah suburb of Lakelands, after riding the bikes on Sunday afternoon.

The men allegedly demanded they hand over the bikes before firing a shot into the engine bay of their car, fleeing in a ute with the two motorcycles in the rear tray.

The armed man is described as being 30-35 years of age, about 178-183cm tall, of slim build, fair skinned with a shaved head and face stubble.

The second offender is described as being 25-30 years of age, fair skinned, of medium build, with brown curly hair in a rat's tail.

Members of the public are urged not to approach the men but instead to call police if they see them.