Police are still investigating a crash which has killed at least two people in North Boyanup on Sunday afternoon.
About 2.45pm, a black Ford Territory collided with a red Nissan X-trail and a silver Mazda 6 sedan that was travelling behind the Nissan on the South Western Highway.
As a result of the collision the Nissan X-trail and Mazda sedan left the road and came to a stop on the grass verge of the highway.
The Ford Territory had six occupants, came to a stop in the middle of the highway.
The driver of the Ford Territory, a 57-year-old woman and a rear passenger, a 2-year-old child died as a result of injuries received in the crash.
A 30-year-old woman who was a front seat passenger in the Territory, received critical injuries and was taken by ambulance to Bunbury Regional Hospital.
Three other passengers, children aged between three and 12 years were conveyed to Bunbury Hospital with minor injuries.
The driver of the Mazda 6, a 39-year-old woman was airlifted by the RAC Rescue helicopter to Royal Perth Hospital with critical injuries.
A six-year-old child who was a passenger in the Mazda was taken to Bunbury Hospital for medical treatment.
The driver of the Nissan X-trail, a 54-year-old woman and her 74-year-old female passenger received minor injuries that did not require medical treatment.
Major Crash investigators would like to speak to anyone who saw the crash, or the three vehicles involved travelling in the area prior to the crash.
Anyone with information or dash-cam vision relating to this crash is ask to come forward and contact Crime Stoppers on 1800 333 000 or online at www.crimestopperswa.com.au.