The male driver of a Toyota Corolla died in hospital after his car left the High Road in Riverton and smashed through a brick wall just before 1.30pm.
He suffered serious injuries in the crash and was taken to Fiona Stanley Hospital where he was pronounced dead.
It is believed the driver may have suffered a heart attack before the crash.
High Road was closed to eastbound traffic between Leach Highway and Centaur Street for several hours.
A second person has died in a crash in Jandakot this afternoon.
It is understood the male driver was the only person in car when it hit a power pole on Jandakot Road, near the Coonadoo Court intersection, about 4.20pm.
He died at the scene.
Police major crash officers are investigating.
No other details are available at this stage.