Firefighters were last night battling to save two South West towns from what authorities fear will become the biggest bushfire in WA's history.
The State Government asked for more help from the Eastern States to fight the blaze, which last night had torn through about 70,000ha of forest with 50-year-old fuel loads.
The biggest fears were for the town of Northcliffe, which Emergency Services Minister Joe Francis conceded was "proving very difficult to defend" because it was surrounded by forest and there was a lack of water in the area, so it had to be trucked in.
There were also concerns that the out-of-control blaze would burn through Northcliffe and reach Pemberton today.
A Department of Parks and Wildlife spokeswoman said the majority of Northcliffe's residents had been evacuated. She said about 30 people remained because they felt they could "adequately defend their homes".
Mr Francis said the best-case scenario was that fire crews would get on top of the fire today.
Two properties, only one lived in, had been lost.
"This is the biggest fire in decades in WA," Mr Francis said.
"Even if we get lucky with the weather, this is a fire that is going to take days and days - if not weeks - to finally extinguish and get under control."
The 170km perimeter blaze has raged for six days.
Judy Ford, who lives 5km north of Northcliffe, said there was a charcoal-coloured "bank of smoke" above the threatened town as she prepared to defend her home.
Details emerged of a dramatic rescue by the Department of Fire and Emergency Services urban search and rescue team, who saved a woman trapped on her property west of Northcliffe on Tuesday night.
The rescuers were hailed by the woman's desperate husband as they drove down a dirt track.
DFES deputy incident controller John Tillman said the town of Windy Harbour, where about 60 residents, firefighters and police had been trapped, was safe.
He said the eastern front of the fire had broken containment lines and jumped the closed South West Highway last night.
"We are dealing with fuels so old that when it takes off, you are talking flame heights 30m above the trees," Mr Tillman said.
Mr Gregson said extra resources - two aerial tankers and at least one air crane from Victoria - were due to arrive this morning. "This is in line with our commitment to do whatever it takes to fight this fire," he said.
Resources were stretched further by a fire in the southern part of Lower Hotham in the Shire of Boddington. The blaze was sparked by lightning on Saturday but warnings were upgraded because of its intensity and the fire jumping containment lines on two sides, putting homes under threat.
"On the way back as I flew past the Boddington fire, I snapped a photo out the window of the plane and it looked like an atomic bomb had gone off," Mr Francis said.
More than 130 firefighters from Victoria arrived late yesterday in time to start their first 12-hour shift at 6pm, giving about 50 tired WA firefighters a rest.
Manjimup Shire President Wade De Campo said that Prime Minister Tony Abbott had called him last night to express his concern about the fires.
He had also offered Federal Government assistance.
Mr De Campo said the military would be putting up tents in Manjimup to house firefighting volunteers.