Authorities say a bushfire that posed a possible threat to lives and homes in East Rockingham and Kwinana was deliberately lit.
The fire started near the intersection of Patterson Road and Charles Street around 3.18pm on Monday.
It reached a watch and act alert with nearby residents urged to leave their homes or get ready to actively defend them.
Firefighters managed to bring the blaze under control within a couple of hours.
It had burnt through 2.5 hectares of bushland.
Anyone who saw any suspicious activity at the time of the fire should contact Crime Stoppers on 1800 333 000.

A bushfire advice remains for the area. PIC: DFES
Peel Cavaliers break nine-year drought to win Country Championships
City tees up new vision for Kwinana Golf Course
Warnbro man charged with more child abuse, animal cruelty offences
Teen threatened, robbed by offenders on e-scooter in Mandurah
Labor candidate for Secret Harbour Georgia Tree vows to fight for locals
Safety Bay man arrested after Perth police pursuit comes to crashing end
Port Kennedy before and after school care provider fined $33k after 'distressed' boy left alone in room
Dog ball library created at Dawesville beach in memory of beloved pet
WATCH: Police investigate South Yunderup motorbike theft as sellers warned to stay vigilant