Sixty firefighters are battling a fire burning in bushland in the northwestern part of Ellenbrook, near the Gnangara Forest, on Monday morning.
The Department of Fire and Emergency Services has issued a Bushfire Advice alert, saying there is no threat to lives or homes at present but there is a lot of smoke in the area.
The fire was reported about 9am and has so far burnt through 10 hectares of bushland.
It is moving slowly southwest and has not yet been contained or controlled.
Access is proving problematic because of the density of the bush, so earthmoving equipment from DFES and the Department of Parks and Wildlife has also been sent to the scene.
No roads have been closed, but residents should take care while driving through the area.
The public is advised to drive slowly with headlights on and if emergency services staff issue directions, to follow them.
If you cannot see properly pull over, turn on hazard lights and wait until the smoke clears, DFES says.
Those with respiratory conditions affected by smoke should call their doctor or 1800 022 222.
The cause of the fire is unknown.
