Los Angeles firefighters are bracing for high winds with gusts that could fuel two monstrous wildfires that have already levelled entire neighbourhoods, killed at least two dozen people, and burned an area the size of Washington DC.

Hurricane force winds of 75mph (120km/h) were possible from early in the morning, with 50-70 mph gusts expected through Wednesday, said David Roth, a meteorologist with the National Weather Service's Weather Prediction Center.

A red flag warning was in effect as dry, dangerous Santa Ana winds picked up speed.

More than 8500 firefighters attacked the fires from the air and on the ground, preventing the conflagrations at either end of Los Angeles from spreading overnight.

California Senator Adam Schiff talks fire support at evacuation centre. – AP

Los Angeles City Fire Chief Kristin Crowley urged people to stay away from burned neighbourhoods filled with broken gas lines and unstable buildings.

"This setup is about as bad as it gets," and Crowley told Angelenos. "We are not in the clear."

State authorities were pre-positioning firefighting crews in Los Angeles as well as other Southern California counties that were also under elevated fire danger.

Highlighting the risks, a new small but fast-moving fire erupted in scrubland in the bed of the Santa Clara River in Ventura County, northwest of Los Angeles. 

Ground crew and several helicopters were working to contain the so-called Auto Fire, which had razed over 56 acres and was burning near a golf course but not yet threatening homes.

The two main wildfires erupted on Tuesday last week, fuelled by hurricane-force winds bringing dry air from the inland deserts.

At least 24 people have died in the fires since then, according to the Los Angeles County Medical Examiner.

The wildfires have destroyed or damaged more than 12,000 structures, turning entire neighbourhoods into smouldering ash and piles of rubble, leaving an apocalyptic landscape.

A Cal Fire engine crew hoses down a hotspot in Altadena. – AP

More than 92,000 people in Los Angeles County are under evacuation orders – down from a previous high of more than 150,000 – while another 89,000 faced evacuation warnings.

The Palisades Fire, which wiped out upscale communities on the western flank of Los Angeles, burned 23,713 acres (96 sq km) and was 14 per cent contained, a figure representing the percentage of the fire's perimeter that firefighters have under control.

The Eaton Fire in the foothills of the San Gabriel Mountains east of the city consumed another 14,117 acres (57 sq km) and was 33 per cent contained, the California Department of Forestry and Fire Protection (Cal Fire) reported.

A third fire of 799 acres (3.2 sq km) north of town was 95 per cent contained and three other fires in the county have been fully brought under control in recent days.

Volunteers continue to support the fight against wildfires. – AP

The Eaton fire damaged the Altadena home of Lorraine Bryan, 63, and destroyed two other dwellings on her property. She said she worries about getting additional doses of insulin that she needs to manage her diabetes.

"I'm worried about insurance and about rebuilding and getting back on my feet," Bryan said, standing in the doorway of her charred home.

"I need my medication. I'm trying to see who can help us."

Deputies are finding human remains every day as they search through burned-out parts of Altadena, where the Eaton fire first ignited, Los Angeles County Sheriff Robert Luna said.

"It is a very grim task," Luna said, adding that he expected the confirmed death toll to rise in the days ahead.

California Governor Gavin Newsom has said the firestorm could rank as the most devastating natural disaster in US history. It is already the costliest wildfire in terms of insured losses.

A worker surveys the damage from the Palisades Fire. – AP

Los Angeles County District Attorney Nathan Hochman said 10 people had been arrested in connection with the fires.

Nine people were arrested for residential burglaries of fire-stricken areas. One other person was arrested for arson, for allegedly attempting to light a tree on fire in the city of Azusa, about 20 miles (32km) northeast of downtown Los Angeles.

US Senator Adam Schiff, a Democrat from California, said there was "a special place" for looters.

Flanked by law enforcement personnel, he added: "And if the folks behind me have anything to say about it, there'll be a special place in jail for you too."

Meanwhile, the Los Angeles Department of Water and Power is being sued on claims that it failed to properly manage water supplies critical to fighting the deadly Palisades Fire, a court filing showed.

Residents who sued allege the department should have maintained water in a nearby reservoir, which was dry at the time the fire first erupted last Tuesday.

President Joe Biden attends a briefing on the federal response to the wildfires across Los Angeles. – Reuters

In the face of the devastation, hundreds of volunteers gathered at the Santa Anita Park racetrack on Sunday in Arcadia, close to the Eaton Fire, hauling in boxes of food, clothing and diapers for distribution to victims. Volunteers waited in long lines for an opportunity to help.

The Rose Bowl in Pasadena has turned into a base camp for fire trucks and firefighters from all over California and the West to fight the nearby Eaton fire. Fire trucks are lined up in the area before they head over to the fire and firefighters are sleeping on the grounds and eating their meals under tents.

"Our hearts ache for the 24 innocent souls we have lost in the wildfires across Los Angeles," said US President Joe Biden. 

He announced additional disaster assistance for California, covering costs for debris removal and emergency protective measures.

But top Republicans in the US Congress are considering imposing conditions on disaster aid, accusing the state's Democratic leadership of mismanaging water resources and forests.

President-elect Donald Trump planned to visit the disaster zone after he is inaugurated next week, a source familiar with the planning said.

California Governor Newsom and other top Democrats in the state have come under withering criticism for their handling of the fires.

President-elect Donald Trump plans to visit the disaster zone after he is inaugurated next week, a source familiar with the planning said.

With thousands of homeowners facing a costly rebuilding, large commercial banks including JPMorgan Chase and Bank of America have announced plans to ease mortgage repayment conditions for the afflicted. Insurers are looking at historic losses.