In a suburban Perth park, flames devoured trees and came close to houses in a bushfire that police are now saying was deliberately lit.

Atwell resident Mackenzie Milligan said he was furious to hear the fire was believed to have been started by an arsonist.

The heat sparked a fire in his air conditioner and singed his back lawn. He was at work but his neighbours stepped in to stop the situation getting worse.

"(I’m) very angry,” he said.

“There's no words to describe the stupidity of someone to do this.”

Camera Icon Residents worked to extinguish flames before firefighters arrived. Credit: 7NEWS

Dylan Cash ran to help when fires started in an alleyway near his home on Friday.

“It's just getting ridiculous now, like Australia's on fire for Christ's sake,” he said.

“You gotta do what you gotta do, just jump in and get it done.”

Mick Levco said, “we got the garden hoses and stretched them over there and jumped his fence.”

Justin Evans said he tried to help by grabbing as many hoses as he could.

Camera Icon Dylan Cash and Justin Evans. Credit: 7NEWS

Dylan Hammond said, “there was probably 40, 50 people on the street all trying to help out where they could.”

Chris McAlpine said, “it was quite spectacular to see, through all the devastation that did happen to see the community come together like that it's amazing to see.”

A resident supplied security vision to the arson squad showing a person calmly walking away from an area close to where the blaze started.

Camera Icon Credit: 7NEWS

The Atwell bushfire was just one of several fires that started around Perth yesterday with police also investigating a blaze in Wellard.

There was more devastation as a home went up in flames in Thornlie, causing $350,000 in damage.

Investigators said the damage was too severe to say how that fire started.

Late last night there was another fire emergency in Gosnells, with two grandparents and their grandchildren trapped inside a burning home.

They were saved by heroic neighbour Lisa White.

Camera Icon Lisa White. Credit: 7NEWS

“The grandmother passed me the baby over the fence and the the four-year-old over the fence ... I just put them in my house...shut all the doors so they didn't cop the smoke,” she said.

Three people were taken to hospital for smoke inhalation.

Investigators are looking into the cause of that fire.

Meanwhile, WA's Islamic Council has raised $3500 for victims of Australia's bushfire crisis.

Dozens of people attended the fundraiser - donating what they could for the nation's recovery effort.

Zouber Sayed said, “our fellow Australians are in difficulty and tribulation, so it's our duty to step in and assist and to help.”