UPDATE 4:30pm: A bushfire burning in Bullsbrook has been brought under control, but firefighters will continue to monitor the situation overnight.
About 50 volunteer and career firefighters have been fighting the blaze, burning near Asher and Della North Roads, since it was reported about 8:45am today.
Two water bombers and a helicopter were used to protect crews and homes, but have since been released.
But while the fire is under control, the Department of Fire and Emergency Services has told residents to watch for signs of fire and close all doors and windows.
This includes people in and near Old West Road, Della North Road, Kirby Road, Asher Road, north of Neaves Road including the Maze Fun Park, Pine Road and Bingham Road, and surrounding areas in the western part of Bullsbrook in the City of Swan.
Residents should also have a plan on whether they will stay and defend their home or evacuate if the fire moves closer.
Evaporative air conditioners should be switched off but water should be kept running through the system if possible, the department alert said.
Motorists are also asked to avoid the area, reduce speed and drive carefully in smoky conditions.
Updates will be released on the department website www.dfes.wa.gov.au. Residents can also call 1300 657 209 for information.