Towns have been wiped out and hundreds of thousands of people fled their homes as wildfires continue to burn across the USA’s west coast, killing dozens of people.

About half a million people in the state of Oregon are under evacuation orders as extreme, wind-driven wildfires tear through hundreds of thousands of hectares.

About an eighth of the state’s total population has been ordered to flee, as Portland suburbs came under threat from the state’s biggest blaze, the state Office of Emergency Management said.

Damaged homes and cars in a mobile home park destroyed by fire in Phoenix, Oregon.

Thousands more were displaced in the neighbouring states of Washington and California, north and south of Oregon.

Since Monday 11 people have died from fires in California while four were killed in Oregon and a 1-year-old boy died in Washington state, police reported.

That takes the past month’s death toll to at least 24, with most of them in recent days.

Wildfires have burned through more than 12,500 square kilometres in California. Photo: AP

Oregon’s governor described the relentless fires as “unprecedented”, with nearly double the number of acres burned this year than the annual average from the last decade.

Oregon bore the brunt of nearly 100 major wildfires raging across western states, with about 3000 firefighters battling nearly three dozen blazes and officials saying about twice as many people were needed.

Firefighters said unusually hot, dry winds out of the east supercharged blazes, spreading flames from community to community, and then from house to house.

The Oregon blazes tore through multiple communities in the Cascade mountain range as well as areas of coastal rainforest normally spared from wildfires.

MASS EVACUATIONS: A wildfire swept through this neighborhood in Talent, Ore., on Thursday, one of several statewide forcing 10% of Oregon’s population to evacuate, according to the state’s Office of Emergency Management. https://t.co/F2NxtIrway pic.twitter.com/VW6Ck5DAHn

— CBS Evening News (@CBSEveningNews) September 11, 2020

In eastern Washington state, a fire destroyed most of the tiny farming town of Malden.

In central Oregon search-and-rescue teams entered devastated communities in the Santiam Valley to look for missing people.

To the south, a string small communities along Interstate 5 near Medford were reduced to ashes after embers from a wildfire blew for kilometres.

Aerial view of some of the hundreds of homes destroyed by fire in Phoenix, Oregon. Photo: Getty

Police have opened a criminal arson investigation into at least one Oregon blaze, the Almeda fire, which started in Ashland near the border with California and incinerated several hundred homes in adjacent communities along Bear Creek, Ashland Police Chief Tighe O’Meara said.

At least four Oregon police departments warned of “fake” online messages appearing to be from law enforcement that blamed rival political extremist groups Antifa and Proud Boy activists for starting the fires.