Firefighters raced to contain the frontiers of two Los Angeles wildfires that burned for the sixth straight day on Sunday, taking advantage of a brief respite in hazardous conditions before high winds were expected to fan the flames anew.

At least 24 people have died in what California Governor Gavin Newsom said could be the most devastating natural disaster in U.S. history, one that has destroyed thousands of homes and forced 100,000 people to evacuate.

Flames have reduced whole neighborhoods to smoldering ruins, leveling the homes of the rich and famous and ordinary folk alike, and leaving an apocalyptic landscape. Officials said 12,300 structures have been damaged or destroyed.

"L.A. County had another night of unimaginable terror and heartbreak," Los Angeles County Supervisor Lindsey Horvath said.

Aerial firefighters, some of them scooping water out of the Pacific Ocean, dropped water and retardant while land crews with hand tools and hoses held the line of the Palisades Fire as it encroached on the upscale Brentwood section and other populated areas of Los Angeles.

That fire on the western side of town has consumed 23,713 acres (96 sq km) or 37 square miles and stood at 11% contained, a figure representing the percentage of the fire's perimeter that firefighters have under control.

The Eaton Fire in the foothills east of Los Angeles scorched another 14,117 acres (57 sq km) or 22 square miles - itself nearly the size of Manhattan - and firefighters increased the containment to 27%, up from 15% a day earlier.

North of the city, the Hurst Fire was 89% contained, and three other fires that had ravaged other parts of the county were now 100% contained, the California Department of Forestry and Fire Protection (Cal Fire) reported, though areas within the containment lines may still be burning.

SEVERE WINDS RETURN

Firefighters got a temporary break from the weather this weekend as Santa Ana winds, which reached hurricane force earlier in the week, finally eased. The dry winds originating from the inland deserts had fanned flames and blew embers up to 2 miles (3 km) ahead of the front lines.

But, in an area that has not received any rain of note since April, the National Weather Service forecast Santa Ana winds of up to 50 to 70 miles per hour (80 to 112 kph) would resume on Sunday night and last through Wednesday.

Officials warned the entire Los Angeles County population of nearly 10 million that anyone may be ordered to evacuate from the flames and toxic smoke.

By Sunday, more than 100,000 people in Los Angeles County had been ordered to evacuate - down from a previous high of more than 150,000 - while another 87,000 faced evacuation warnings.

"These winds combined with low relative humidities and low fuel moistures will keep the fire threat in all of Los Angeles County very high," Los Angeles County Fire Chief Anthony Marrone told a press conference, adding that evacuated areas may not be reopened until red flag conditions are lifted on Thursday.

Even so, schools except some in mandatory evacuation zones would reopen on Monday, after closing for all 429,000 students in the Los Angeles Unified School District on Thursday and Friday, Superintendent Alberto Carvalho announced.

Newsom told NBC News the fires were likely to be the worst natural disaster in U.S. history "in terms of just the costs associated with it." The Los Angeles County Medical Examiner reported 24 deaths from the fires.

Private forecaster AccuWeather has estimated the damage and economic loss at $135 billion to $150 billion.

To help expedite the monumental rebuilding effort ahead, Newsom signed an executive order on Sunday temporarily suspending environmental regulations for destroyed homes and businesses.

Active duty military personnel are ready to support the firefighting effort, FEMA Administrator Deanne Criswell said in a series of Sunday television interviews, adding the agency has urged residents to begin filing for disaster relief.

Firefighters from seven states, Canada and Mexico have already converged on the Los Angeles area to help fire departments from around the state.

HIGH ANXIETY

In Altadena on the edge of the Eaton Fire, Tristin Perez said he never left his home, defying police orders to evacuate as the fire raced down the hillside.

Instead, Perez insisted on trying to save his property and his neighbors' homes.

"Your front yard is on fire, palm trees lit up – it looked like something out of a movie," Perez told Reuters in an interview in his driveway. "I did everything I could to stop the line and save my house, help save their houses."

His one-story yellow duplex survived. So did two more homes next door. Across the street, entire houses burned to the ground.

"A lot of these areas still look like they were hit by a bomb. There are live electrical wires, gas lines and other hazards," said Los Angeles County Sheriff Robert Luna.

Zuzana Korda was evacuated from her home in the Fernwood neighborhood in Topanga, northwest of Los Angeles. Speaking outside a temporary assistance office at the West Hollywood Public Library, she said her landlord told her the family home was still standing, but she was anxious.

"We've left everything behind. We have no insurance," Korda said. "We stand to lose everything."