Two trapped following five-car crash in West Leederville, Perth

A heavily pregnant woman is being treated following a five-car crash in Perth, St John Ambulance says.

Emergency services are working to free two others trapped in vehicles after the accident on the corner of Cambridge and Loftus Streets in West Leederville, in which a 4WD collided with four other cars.

Police, firefighters and four ambulances are at the scene.