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.