The Arson Squad is investigating the cause of a house fire in Orelia.
The blaze broke out around midday on Monday at the home on Nathaniel Way.
The fire caused extensive damage to the property leaving a bill of $250,000.
It is understood a family of seven lived at the home, including a woman, her son and daughter, four grandchildren and a foster child.
Detectives are asking any motorists who were driving along Christmas Avenue and Nathaniel Way in Orelia between 12pm and 12.30pm on Monday, who have dash-cam vision to come forward.
Anyone with any information relating to this fire is asked to call Crime Stoppers on 1800 333 000 or report online at www.crimestopperswa.com.au.
Rewards of up to $50,000 are available for information that leads to the apprehension and subsequent conviction of an arsonist.

'Prognosis terrifying' for young boy struck by car in Cooloongup
K9 Rescue's long-term resident in desperate search for loving home
West Coast Radio announcer Darragh O’Dea takes out Best Local Show at Australian Audio Awards
Lucky escape for two people after boat smashes into Mandurah Estuary Bridge
Secret Harbour Golf Links to host WA's most prestigious golf tournament
Upgrades begin on Kwinana Loop Trail
Shire of Harvey councillors vote in favour of city status
Erskine syndicate shares in division one Lotto win
Man accused of chasing down boy in Greenfields car park before assaulting him and stealing bicycle