Update: Firefighters are battling an out-of-control fire in parts of Forrestdale, Banjup and Aubin Grove.
There are reports that four homes have already come under ember attack.
By 10.10pm tonight, the bushfire was no longer travelling. It was contained but not under control.
Earlier DFES downgraded the alert to Watch and Act status for people in Banjup, Aubin Grove and Atwell in the City of Cockburn and Forrestdale in the City of Armadale
DFES said there was a possible threat to lives and homes as a fire was in the area and conditions were changing.
It said residents needed to leave or get ready to actively defend.
The blaze has burnt through about 300 hectares in Banjup and Forrestdale.
The bushfire was moving a westerly direction and is burning in heavy swampland.
The fire started between Taylor Road and Nicholson Road and is burning towards Aubin Grove and Atwell.
A bushfire watch and act remains for people in an area bounded by Tapper Road west to the Kwinana Freeway in Atwell.
A bushfire advice has been issued for people in Success and Hammond Park.
People in these areas you need to be aware and keep up to date.
The fire was reported today at 12.12am.
The blaze was contained this morning but a flare up has occurred which now poses a possible threat.
The cause of the fire is unknown.
Water bombers are being used to help about 200 career and volunteer Fire and Rescue Service, Bush Fire Service and Department of Parks and Wildlife firefighters on the ground.
A relocation centre has been set up at the Armadale Arena on the corner of Townley Street and Forrest Road in Armadale. There will be a community meeting held here at 6.30pm today.
Several roads have been closed including Nicholson Road in both directions from Armadale Road to Rowley Road in Forrestdale, Rowley Road southbound off ramp closed at Kwinana Freeway, Taylor Road and Gibb Road.
The Russell Road southbound off ramp at Kwinana Freeway has been opened.
Drivers should avoid Kwinana Freeway southbound, after Berrigan Drive, due to heavy smoke.