Four people, including two women in their 60s, are in hospital after being injured in a terrifying attack by a mob in suburban Perth.

West Australian police said about 10.45pm (WST) on Wednesday, the quartet were travelling in a car along Cornwall Street in Lathlain when two men stood in the middle of the road blocking their path.

After swerving to avoid them, the car crashed into a kerb. Another group of up to six people then surrounded the vehicle.

Heavy objects were thrown at the car, police said, before three men dragged the 34-year old male driver from the car and assaulted him.

A 28-year-old female passenger in the front seat was also dragged from the car and struck in the face.

Both were also assaulted with a tree branch.

Two other passengers, a 63-year-old woman and a 61-year-old woman, were then ordered out of the vehicle, with the older woman also assaulted.

The mob then fled, with all four victims needing treatment at Sir Charles Gairdner Hospital.

The offenders are described as dark-skinned.

Anyone who can assist in this investigation is asked to call Crime Stoppers on 1800 333 000.