Update (2.50pm): WA Police have confirmed a female occupant has died as a result of the crash.
St John Ambulance have transferred another two females to Royal Perth Hospital in a critical condition.
Previous (1pm): Three teenagers are in a critical condition after a single-vehicle crash along White Hill Road in Bouvard on Tuesday afternoon.
About 12.35pm, a car rolled in to shrub on the south side of the white gravel road.
A crew from Falcon Volunteer Fire Rescue found a young woman trapped in the vehicle when they arrived at the scene.
A Department of Fire and Emergency Services spokeswoman said two crews from the Falcon station and two from Mandurah Career Fire Rescue Service were in attendance.
Two St John’s Ambulance crews were also at the scene treating the teenagers, while police interviewed bystanders.
A St John Ambulance spokeswoman said a female patient was taken to Peel Health Campus, with another patient transferred to Royal Perth Hospital.
Major Crash officers will investigate the incident.
White Hill Road is closed in both directions, with motorists advised to avoid the area.
