An 18-year-old man was crushed between two 4WDs while helping tow a a bogged vehicle in Bouvard last night.
A police spokeswoman said about 8.30pm a man was driving along the beach back towards White Hill Road when he became bogged and called a friend to help free his vehicle.
The 20-year-old friend arrived with the 18-year-old and towed the man's 4WD from the bog.
Both vehicles were parked on a downward slope.
After the car was freed, the injured man was helping to unhook the strap between the two vehicles when the front car rolled backwards, crushing the teenager between the two cars.
He fractured his pelvis and was airlifted to Royal Perth Hospital where he remains in a stable condition.