Major Crash officers are investigating a serious traffic crash that occurred on Saturday in Quedjinup.
Police say the driver of a grey Audi A3 convertible travelling east on Biddle Road lost control and collided with a tree near the intersection of Quedjinup Drive at around 4.20pm.
The 63-year-old male driver and 55-year-old female passenger received serious injuries and were conveyed to Royal Perth Hospital for treatment.
Investigators are seeking assistance from the members of the public who may have observed the crash or may have seen the Audi prior to the crash.
Anyone who may have dash camera footage or information is asked to contact Crime Stoppers on 1800 333 000 or report online at www.crimestopperswa.com.au