Police are investigating a crash in Cowaramup in which a woman received fatal injuries.
The crash occurred around 11.30pm on the Bussell Highway, at around three kilometres south of Cowaramup, and involved three vehicles.
It is believed that two vehicles were involved in a head-on collision, before another vehicle later crashed into the two.
Two males and a female were transported to Busselton Hospital with non-life threatening injuries and have now been discharged.
A female who was a driver in one of the vehicles was taken to Margaret River Hospital and later flown to Royal Perth Hospital.
The deceased woman is believed to be a 22 year old and she died at the scene of the crash.
Anyone who can assist with this investigation is asked to call crime Stoppers on 1800 333 000.