Winds are forecast to gust up to 70 mph, with relative humidity as low as 8%.
LOS ANGELES -- Millions of people across Southern California faced new wildfire warnings Tuesday, and tens of thousands saw their power shut off as strong winds blew across the parched landscape around Los Angeles where two massive blazes have been burning for a week.
Santa Ana winds that began gusting over the mountains before sunrise were forecast to continue with enough force to carry fire-sparking embers for miles and stoke new outbreaks across a region where at least 24 people have already been killed.
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"Life threatening and destructive and widespread winds are already here," LA city Fire Chief Kristin Crowley told a news conference.
Much of Southern California was under an elevated fire risk, with crews on high alert across a 300-mile stretch from San Diego to far north of Los Angeles. Facing the greatest risk were inland areas north of LA, including densely populated Thousand Oaks, Northridge and Simi Valley, home to more than 300,000 people, forecasters said.
Nearly 90,000 households lost electricity as utilities shut off power to prevent their lines from sparking new blazes.
The Palisades Fire, which began in the Pacific Palisades on Jan. 7, has destroyed about 5,000 structures and has been blamed for eight deaths. It's covered more than 23,000 acres and is at 17% containment.
The Eaton Fire north of Pasadena also began on Jan. 7. It's been blamed for 16 deaths and has destroyed or damaged around 7,000 structures. It's burned over 14,000 acres and is at 35% containment.
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The sheriff's department is following 24 missing persons cases, all adults, LA County Sheriff Robert Luna said. The LAPD said it has 13 active missing persons cases, two of whom are believed to be dead.
No more remains were found when crews searched the hard-hit Altadena area on Monday, the sheriff said.
Investigators are still trying to determine what sparked the fires. They could be the nation's costliest ever. Government agencies haven't provided preliminary damage estimates yet, but AccuWeather, a company that provides data on weather and its impact, puts the damage and economic losses at $250 billion to $275 billion.
Here's a closer look at what to know about the fires.
The next 24 hours will be very dangerous as high winds blow through the Los Angeles area, Luna warned on Tuesday morning.
He urged residents to follow evacuation orders, noting that many people who waited until the last minute to evacuate last week suffered significant burns.
"We don't want you to impact your own life or the life or your loved ones," Luna said.
Tuesday's forecast included a rare warning: The winds, combined with severely dry conditions, have created a "particularly dangerous situation," meaning that any new fire could explode in size.
Gusts will pick up strength in the evening and into Wednesday before decreasing, and red-flag warnings now up from Central California to the Mexican border will remain through most of Wednesday, weather service meteorologist Ariel Cohen said.
The warning began at 4 a.m. local time. Winds were forecast to gust between 45 mph to 70 mph, with relative humidity as low as 8%.
Winds overnight and early on Tuesday were gusting up to 67 mph in the mountains near Los Angeles. The West San Gabriel Mountains saw gusts up to 67 mph, with the Central Ventura County Valley hitting about 66 mph.
On Tuesday and Wednesday, the gusty Santa Ana winds will come in periods.
The strongest gusts were expected Tuesday into the early afternoon, which will then be followed by a break in the evening. More gusty winds are expected Wednesday morning.
It has been so dry that any spark could produce major fire that would grow explosively. The weather in Los Angeles last year and early this year has been the second-driest water year on record to date. Water years are recorded from Oct. 1 to Sept. 2, with records going back to 1877.
After Wednesday, winds will begin to calm down and by Friday and Saturday humidity will come up a bit. There a very small chance for a rain shower Friday into Saturday across southern California.
Weary and anxious residents were told to be ready to flee at a moment's notice. They remained vigilant, keeping an eye on the skies and on each other: Police announced roughly 50 arrests, for looting, flying drones in fire zones, violating curfew and other crimes.
Of those, three people were arrested on suspicion of arson after being seen setting small fires that were immediately extinguished, LA Police Chief Jim McDonnell said. One was using a barbecue lighter, another ignited brush, and a third tried to light up a trash can, he said. All were far outside the disaster zones. Authorities haven't determined a cause for any of the major fires.
Among nine people charged with looting was a group that stole an Emmy from an evacuated house, Los Angeles County District Attorney Nathan Hochman said.
The biggest worry remained the threat from intense winds predicted to reach nearly hurricane force Tuesday in some areas. Now backed by firefighters from other states, Canada and Mexico, crews were deployed to attack flareups or new blazes. The firefighting force was much bigger than a week ago, when the first wave of fires began destroying thousands of homes in what could become the nation's costliest fire disaster.
Kaylin Johnson and her family planned to spend the night at their home, one of the few left standing in her neighborhood in Altadena, near Pasadena. They planned to keep watch to ward off looting and to hose down the house and her neighbors' properties to prevent flareups.
"Our lives have been put on hold indefinitely," Johnson said in a text, adding that they cannot freely come and go because of restrictions on entering the decimated areas. "But I would rather be here and not leave than to not be allowed back at all."
Residents gathered up their pets and family photos in case they had to make a hasty escape. Tabitha Trosen said she was "teetering" on the edge, constantly fearing her neighborhood could be next.
"Our cats are ready to go. We have their carriers by the door prepped with their little stuffed animals and things like that," Trosen said. "It's like, how do I take care of myself, and what are the things that will ground me as a human and remind me of my background and my life and my family."
Planes doused homes and hillsides with bright pink fire-retardant chemicals, while crews and fire engines deployed to particularly vulnerable spots with dry brush.
Los Angeles Mayor Karen Bass and other officials who were criticized over their initial response expressed confidence that the region is ready to face the new threat. The mayor said she was able to fly over the disaster areas, which she described as resembling the aftermath of a "dry hurricane."
Winds this time were not expected to reach the same fierce speeds seen last week but could ground firefighting aircraft, LA County Fire Chief Anthony Marrone said. He warned that if winds reach 70 mph (112 kph), "it's going to be very difficult to contain that fire."
He urged people experiencing homelessness to avoid starting fires to keep warm and said they should seek shelter.
With almost no rain in more than eight months, the brush-filled region has had more than a dozen wildfires this year, mostly in the greater Los Angeles area.
Firefighters have been jumping on small fires that pop up. One such blaze, in a dry riverbed near Oxnard Monday night, was quickly smothered. "We've got helicopters ready to go, to drop water on any new fires," said Andrew Dowd, a spokesperson for the Ventura County Fire Department.
The four biggest fires around the nation's second-biggest city have scorched more than 63 square miles (163 square kilometers), roughly three times the size of Manhattan. Of these, the Eaton Fire near Pasadena was roughly one-third contained, while the largest blaze in Pacific Palisades on the coast was far less contained.
The death toll is likely to rise, Los Angeles County Sheriff Robert Luna said. At least two dozen people remained missing, he said Tuesday. Some people earlier reported as missing have been found.
Just under 90,000 residents in Los Angeles County remained under evacuation orders, half the number from last week.
Hollywood's awards season has been put on hiatus because of the crisis. The Oscar nominations have been delayed twice, and some organizations have postponed their awards shows and announcements without rescheduling.
Take a look at the latest stories and videos on the devastating Southern California wildfires here.
ABC News' Max Golembo and the Associated Press contributed to this report.