A teenage girl was taken to hospital after a serious crash in West Pinjarra on Monday.
About 1pm, two cars collided at the intersection of Greenlands Road and Forrest Highway.
Police closed Forrest Highway as the RAC Rescue helicopter was forced to land.
After the teenager was assessed by St John Ambulance, the rescue helicopter was no longer required.
She was taken to Peel Health Campus with non-life-threatening injuries.
Initial reports suggest the teenager was left trapped in the vehicle after the collision.
A short time later, emergency services were called to a fatal single-vehicle crash in Yarloop.
Police confirmed about 3pm, a car hit a tree on Clifton Road near the intersection of Brockman Road.
The driver was the sole occupant of the vehicle and died at the scene.
A RAC Rescue helicopter was also sent to this incident but was not required.