Child 'stable' after WA car crash

A child injured in a car crash in Perth's southeast is in a stable condition in hospital.

Police said the boy, aged about 12, was a passenger in a car that crashed into a parked vehicle in Forrestdale on Thursday afternoon.

It was initially thought he was a pedestrian but police later confirmed the child was in the back seat and hit his head.

St John Ambulance drove the boy at normal speed to Fiona Stanley Hospital, while the driver was taken to Armadale Hospital.

A hospital spokeswoman told AAP the boy was likely to be discharged later on Thursday.