POLICE hope to capture the person who lit a fire in a state forest on Margaret River's Mowen Road on Thursday.
The bushfire started about 2.30pm and required the hard work of about 30 local firefighters to finally bring the blaze under control by 7pm.
Margaret River Police Sergeant Brett Cassidy believed the fire was deliberately lit.
He said smaller fires were started last Monday and Tuesday and the town would be at risk of a major disaster if the arsonist was not found soon.
"It's a stupid activity in summer," Sergeant Cassidy said.
"This person obviously needs help."
In February, the state government reminded people a $50,000 reward was available for information which helped convict an arsonist.
That reminder followed a spike in the number of bushfires suspected to have been deliberately lit in WA.
It was stated that arson cost Australian taxpayers $1.6 billion each year.
Emergency Services Minister Joe Francis asked people to report any suspicious activity.
"The work of just one arsonist can threaten lives, destroy countless homes and direct resources away from other firefighting and rescue activities," he said.
"The $50,000 reward is available for information which leads to the identification and conviction of people who deliberately light fires.
"If you have seen something or know anything about a suspicious fire, help catch arsonists before they strike by reporting what you know to police."
He urged the public to come forward with relevant information by calling Crime Stoppers on 1800 333 000.