Police Arson Squad detectives are investigating the blaze. (ABC News)
A multimillion-dollar Perth home was engulfed in flames overnight, and graffitied with the words "pay your debt dog", in what authorities are investigating as a possible arson attack.
Fire crews raced to the two-storey property in Mount Pleasant about 3.20am Wednesday morning to respond to the out of control blaze.
A message scrawled on the driveway of the Mt Pleasant home. (ABC News)
Department of Fire and Emergency Services district officer Gareth Deeg said flames were burning on both floors of the home, from the front door all the way to the roof.
"The fire has significantly damaged the property both internally and externally, and unfortunately it's not habitable anymore," he said.
Firefighters took about an hour to extinguish the blaze which caused part of the home's roof to collapse.
The fire caused extensive damage to the upper storey. (ABC News)
The cause of the blaze remains undetermined, and WA Police Arson Squad detectives attended the home to examine the scene.
Neighbour heard 'bangs'
Neighbour Line Davison said she woke up to the sound of two loud "bangs".
"I looked out the window and then I saw fire coming from the back of the house, on the roof," she said.
"I didn't expect that to happen on this nice little quiet street. I was more concerned if there was people inside.
"Then I realised that the people in there, they're on holidays, so that was good."
WA Police confirmed no one was injured in the incident.
Ms Davison said the fire, and the vandalism on the driveway, was completely unexpected.
There was extensive damage inside the home. (ABC News)
"It's a bit scary knowing that that's happening in our street," she said.
The home on Ullapool Road was last sold in 2019 for $2,250,000.