A Watch and Act has been issued for the area around Amarillo Drive in Karnup as a fire threatens at least one home.
Tex Reeks-Skeer Media posted video of helitacs and waterbombers called in to defend property.
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READ NOWA Department of Fire and Emergency Services spokeswoman said the fire was called in about an hour ago.
She said five aircraft (helitacs and water bombers) and 13 fire trucks are attending the fire.
Police are managing traffic on the freeway.
Main Roads have cautioned drivers to take care as there is smoke over the road.
The fire was caused by a lawnmower.