At least four people died in bushfires raging in parts of Western Australia, authorities said Wednesday, with a shocked local community lamenting the "day from hell".

Several fast-moving blazes, sparked by lightning, were burning around Esperance some 750 kilometres (450 miles) southeast of Perth, with hundreds of firemen working round the clock in searing temperatures to put out the first serious fires ahead of the Australian summer.

"Sadly, police have confirmed four fatalities," state Fire and Emergency Services Commissioner Wayne Gregson said, adding that two women and two men, in two separate cars, died trying to escape the flames.

It is not known if the vehicles crashed or caught fire.

"I can also record that at this stage there are three houses or buildings unconfirmed as being lost in those fires around Esperance," said Gregson.

One of the men who died was reportedly a local farmer who had been driving to neighbouring properties to warn people before making his own escape. The other victims were said to be foreign backpackers but police would not confirm this.

Authorities advised local residents of an immediate threat to lives and homes.

"The bushfire is moving in a north-easterly direction. Flames are up to two metres high," the Department of Fire and Emergency Services (DFES) said in an advisory.

"Homes in Salmon Gums and Grass Patch are under threat by fire now."

A bushfire emergency warning was also in place for people in the Stockyard Creek and Mullet Lakes areas around Esperance, with a fire contained but not controlled.

Prime Minister Malcolm Turnbull said the government was ready to offer assistance.

"Summer can be a very challenging and dangerous time in Australia as we know and this is a tragic event," he said.

"We are obviously ready to provide assistance whenever required."

Bushfires are common in Australia's hotter months. "Black Saturday", the worst firestorm in recent years, devastated southern Victoria in 2009, razing thousands of homes and killing 173 people.

- Devastating, absolutely terrible -

Esperance Shire President Victoria Brown said the remote coastal community was in shock.

"It was the day from hell, it was devastating," she told national radio. "They got many of the fires out, but there were a few still burning, and they combined into an inferno.

"This is going to have a massive impact on our community. It is the biggest fire we've had to deal with in this region."

DFES regional superintendent Trevor Tasker said the Salmon Gums fire, whipped up by wind, was the worst he had ever seen and the devastation had left him shocked.

In some areas it was "just total destruction", he told the ABC.

"It's heartbreaking. Where there should be luscious crop there's just blackened ground," he said.

Esperance resident Kerry Greg said he broke down in tears when he heard about the fatalities.

"Can't believe it. It's just devastating, absolutely terrible," Greg, who runs a local service station, told the Nine Network.

"The town's rallied together really, really well. I think everyone's glued to their tellies."

Salmon Gums farmer and bushfire brigade volunteer Mic Fels echoed similar sentiments.

"It's just devastating. You know, the bizarre range of feelings that you have. We got our family out of the house when we realised that our property was in the line of the fire yesterday," he told ABC radio.

"The kids are crying. You're chucking all the things in the car you can think of, like favourite teddy bears and our accounts and photo albums."