Motorists are backed up for several kilometres after a crash on Kwinana Freeway northbound at Berrigan Drive, Cockburn Central.
Police have closed the left lane and vehicles are parked in the left emergency lane with motorists outside their vehicles.
Traffic is backed up to Armadale Road and moving slowly.
A towing service is on site and drivers are urged to approach with caution.
On Wednesday night parts of Mitchell Freeway southbound will be closed for roadworks.
Hepburn Avenue to Warwick Road and Hutton Street to Vincent Street will be closed from 9pm to 4am (Thursday morning).
Ramp closure will be in place from 7pm.
Detours will be in place.
