IT is believed fallen powerlines may have sparked the Toodyay bushfire.
The fire destroyed 37 homes and burnt close to 3000 hectares.
Police investigators say while the investigation into the cause of the fire is continuing, they are confident it was sparked by fallen power lines.
Fire and Emergency Services Authority chief operations officer Craig Hynes said early investigations indicated the initial spark for the fire was near fallen power lines.
"The fire did start near the power infrastructure, but we can't give a cause," Mr Hynes said.
The fire started on Tuesday afternoon and burnt overnight. It was still burning late yesterday, but was being contained.
Premier Colin Barnett has declared the area around Toodyay, 80 kilometres east of Perth, a state natural disaster area.
He has announced a $3000 grant for families left in desperate need by the fires, which will be rapidly delivered through the local council.
Mr Barnett, who owns a hobby farm in the area, said his property was spared from the flames, but friends of his had lost their house.
"Everyone in Toodyay would know someone who has been affected," he said. "It is a very close-knit community."
He urged affected families not to be embarrassed in seeking help.
"Everyone in this state recognises the trauma you have been through in terms of (lost) houses, possessions and memories," Mr Barnett said.
About 200 firefighters - and four helitacs – tackled the blaze yesterday, with cooler temperatures and a light shower easing the fire threat. A tree-felling team is clearing roads.
Meanwhile, more than 10,500 hectares have been burnt out in a bushfire at the Marchagee Track, in the Shire of Dandaragan.
FESA estimates the fire has caused several million dollars damage.
The fire has destroyed three-quarters of one property, damaged several farm sheds and vehicles, and a large part of a sandalwood plantation, but no homes have been lost.
More than 100km of fencing, valued at $250,000 was also destroyed.
About 100 firefighters worked through the night to contain the blaze.
Several roads remain closed, including the Marchagee Track, from the Brand Highway to Watheroo, and Dewar, Mackays and Coalara roads.