Los Angeles wildfires burn out of control as death toll rises to 5

The death toll from Los Angeles wildfires has risen to at least five, officials said, with firefighters overwhelmed by the speed and ferocity of multiple blazes.

Up to 1,500 buildings have burned in fires that have broken out around America's second-biggest city so far on Wednesday, forcing over 100,000 people from their homes.

Hurricane-force winds whipped up fireballs that leapt from house to house in the upmarket Pacific Palisades area, incinerating a swathe of California's most desirable real estate favoured by Hollywood celebrities.

Los Angeles County Fire Chief Anthony Marrone said his crews were overwhelmed by the scale and speed of the unfolding disasters.

"We're doing the very best we can. But no, we don't have enough fire personnel in LA County between all the departments to handle this," he said.

The fire raging in Pacific Palisades had consumed around 16,000 acres as of Wednesday afternoon, taking 1,000 homes and businesses with it.

A separate 10,600-acre fire was burning around Altadena, north of the city, where flames tore through suburban streets.

Los Angeles County Sheriff Robert Luna said five people were known to have perished, with more deaths feared.

"Remember, this is still a very fluid situation, there's zero containment on this fire. I'm really praying we don't find more, but I don't think that's going to be the case," he said.

Water runs short

Vicious gusts pushed the flames, whipping red-hot embers hundreds of metres and sparking new spot fires faster than firefighters could quell them.

As a pall of dark smoke hung over Los Angeles, downed trees and broken branches were hampering movement, and residents were urged to stay off the roads.

Los Angeles Department of Water and Power chief executive Janisse Quinones pleaded with people to save water after hydrants in Pacific Palisades ran dry.

Jay Lund, a professor in civil and environmental engineering at the University of California Davis, said city water tanks are typically designed to be able to put out localised fires, not widespread fires like the ones blazing in Los Angeles.

"It's not a matter of there's not enough water in Southern California, it's a matter of there's not enough water in that particular area of Southern California just for those few hours that you need it to fight the fires," Lund added.

President Joe Biden, who was in Los Angeles with California Governor Gavin Newsom, was briefed on what the president called an "astounding" situation.

"We're doing anything and everything, and as long as it takes to contain these fires," Biden told reporters.

Streets of fire

A new wildfire broke out in scrubland in Los Angeles' Hollywood Hills, LA Fire Chief Kristin Crowley says, adding to five other blazes raging in Los Angeles County and sending A-list actors, musicians and other celebrities among those who are trying to flee.

Having razed perhaps hundreds of multimillion-dollar homes, the Pacific Palisades fire looked set to be one of the costliest blazes on record.

AccuWeather said it estimated up to $57 billion of losses had been caused by the multiple disasters. More than 1.5 million households were without electricity in the region, according to the website outage.us. Utilities in California frequently de-energise lines during high winds to minimise the risk of new fires.

Wildfires are part of life in the US West and play a vital role in nature. But scientists say human-caused climate change is altering weather patterns.

Southern California had two decades of drought that were followed by two exceptionally wet years, which sparked furious vegetative growth — leaving the region packed with fuel and primed to burn.

Meteorologist Daniel Swain said the fierce winds — which have gusted up to 160 kilometres an hour — are stronger than the usual seasonal Santa Ana winds but are not unexpected.

"The winds are the driver, but the real catalyst... is this incredible antecedent dryness," he said.

"The lack of rain and the anomalous warmth and dryness that we've seen the past six months. That's something that we haven't seen in records going back to the 1800s."