The arson squad is investigating a suspicious bushfire that burnt close to homes in Port Kennedy on Tuesday.
Firefighters were called to the blaze along Bayside Boulevard about 1:35pm.
Crews from Secret Harbour, Rockingham, and Success worked to protect homes and extinguish the blaze as it burnt through more than three hectares of bushland.
Police closed Bayside Boulevard and several side streets for more than an hour as waterbombers tackled the blaze from the air and crews battled it on the ground.
The Department of Fire and Emergency Services issued an Alert advice for people in the area.
Residents turned sprinklers on as they tried to prevent burning embers from igniting their properties.
Officers from Strike Force Vulcan believe the fire was deliberately lit.
Investigators are urging anyone with information to contact Crime Stoppers on 1800 333 000.
Rewards of up to $50,000 are available for information that leads to the identification and conviction of an arsonist.