A flat-bed truck was stolen in Bassendean and pursued by police early this morning before side-swiping a police car and crashing into a tree in Wattle Grove, police allege.
The alleged driver of the truck is believed to have had his leg amputated because of injuries received in the crash.
A police spokeswoman said officers responded around 3am to reports of a stolen flat bed truck which had allegedly been taken from a concreting business on Guildford Road in Bassendean.
"Shortly after, the vehicle was seen by police on Collier road in Guildford and failed to stop when called upon," the spokeswoman said.
Police pursued the truck.
"During the pursuit the truck allegedly side-swiped a police vehicle. No police officers were injured.
"A tyre deflation device was then deployed. A short time later the truck hit a tree at the intersection of Welshpool Road and Lewis Road in Wattle Grove."
A 29-year-old woman of Rivervale, who was the passenger in the vehicle, was not hurt.
The driver, a 41-year-old man of East Perth, received extensive leg injuries and was taken to Royal Perth Hospital by ambulance.
It is believed that his injuries have since led to the amputation of one leg below his knee.
Major Crash officers and Internal Affairs Unit officers will investigate the incident.