A four-car pileup is blocking one citybound lane of the Northern Motorway near the Greville Rd offramp.
A police spokeswoman said four people suffered "status 4" injuries, described as not serious. Ambulances attended but have now left.
The pileup occurred just before 6pm just after McClymonts Rd, about 400m north of the Greville Rd offramp.
Police originally advised citybound motorists to consider diverting via State Highways 18 and 16, but only one lane is now blocked and traffic is moving.
Meanwhile a truck has broken down in a citybound lane coming in on the Southern Motorway close to the Greenlane offramp. The truck has been moved off the road.