Arson Squad probing six deliberately lit fires that triggered WA emergency warning

The Arson Squad is investigating six deliberately lit fires that triggered an emergency warning for Western Australia's south west.

Two blazes in Yallingup and Injidup threatened lives and homes around 6.30pm yesterday.

More than 100 firefighters were called to battle the flames before a downpour of rain had them under control.

One of the fires at the Duckworth campsite was quickly deemed out-of-control and reached within just three kilometres from homes.

Authorities are treating the fires as suspicious, particularly given the number of ignition points.

However, 9News understands there is so far no evidence of criminal behaviour.

"Investigators will be considering everything including historic fires and looking at the links to those and this," WA Police Superintendent Geoff Stewart said.

WA Police are now calling on the community to come forward with any information that may lead to an arrest and prosecution.

"If someone has deliberately done it, deliberately done it, well then that is a disgusting, deplorable, disgraceful act," WA Premier Mark McGowan told the media today.

"And no doubt the Arson Squad will hunt them down and they'll go to jail."

The blazes come in the same week 86 homes in WA's south were destroyed in emergency level fires.

Meanwhile, a truck convoy has driven from the Wheatbelt to Perth Hills to deliver much needed supplies to farmers who've lost everything in the recent bushfires.