There are reports at least two cars ablaze on the Kwinana Freeway in the northbound emergency lane near Rowley Road.

The freeway northbound is closed in the vicinity while emergency services extinguish the blaze and Main Roads is advising motorists to avoid the area.

It's understood there was a crash just before midday with reports of up to four vehicles involved.

There are no reports so far of any injuries, although St John Ambulance has been called to the scene.

Images captured by a bystander shows a car engulfed in flames with a huge plume of black smoke as a number of motorists stop to assist the occupants.

More to come.