While the flames were within sight of the Getty Center, museum officials said in a statement they're confident their renowned gallery would be spared: "We have activated our full emergency response. Our thoughts are with neighbors and first responders."
The museum, which is normally open on Mondays, was closed because of the fire.
"Many have asked about the art — it is protected by state-of-the-art technology," according to the museum. "The safest place for the art and library collections is inside."
"This is a fire that quickly spread," Mayor Eric Garcetti told reporters. "We have a lot of amazing heroes that were in our fire stations who rolled out immediately."
The so-called Getty Fire had charred 618 acres by early Monday afternoon, Garcetti said, marking a slowing spread of the blaze that had been at 500 acres three hours earlier.
The mayor said firefighters are battling flames in "some of the most challenging topography of Los Angeles." Firefighters also had to contend with winds gusting at more than 20 mph and pushing flames, officials said.
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Garcetti and fire investigators did not immediately disclose what might have ignited the fire, but the mayor ruled out homeless encampments in the West L.A. hills as a possible cause.
At least five homes had been destroyed and "I anticipate that number will climb in the coming hours," Los Angeles City Fire Chief Ralph Terrazas said.
In neighborhoods hardest hit by the blaze, firefighters were "overwhelmed" and "had to make some tough decisions on which houses they were able to protect," said Terrazas.
The chief recalled seeing homes perfectly untouched standing next to ones which had burned down.
"Many times it depends upon where the ember lands," Terrazas said. "I saw homes that were adjacent — that were totally destroyed — without any damage."
Southern California just ended a practically rain-free summer, making hillside brush dry and even more at risk of burning.
It’s been 124 days since the last rain fell in downtown and 95 days since rain at the Los Angeles International Airport.
“It’s a dangerous season right now,” Terrazas said. “We’ve not had any significant rainfall for a period of time. So that’s why we’re very, very concerned.”
It'll be a matter of days, not hours, before this blaze is completely extinguished, authorities said. But firefighters hope to get as much contained by Wednesday when winds gusting up to 70 mph are forecast for Southern California.
"We do expect Wednesday the wind to pick up dramatically, some of the strongest Santa Ana winds," Garcetti said.
"If you're in the mandatory evacuation zone and you're still there watching this, you're an idiot. Get the hell out," City Councilman Paul Koretz, whose district is just beyond the evacuation zone, said.
"It's way too dangerous. (For) people to stay behind are just endangering themselves and not helping."
"Evacuated... Apparently, everything around me is burning the f--- down. Rough week," he wrote.
Former Gov. Arnold Schwarzenegger said he went running from his home at about 3:30 a.m.
"If you are in an evacuation zone, don't screw around. Get out," Schwarzenegger said. "Right now, I am grateful for the best firefighters in the world, the true action heroes who charge into the danger to protect their fellow Californians."
The Los Angeles premiere of Schwarzenegger's new movie, "Terminator: Dark Fate," was postponed on Monday.
Even though it was set to screen at TCL Chinese Theatre in Hollywood, which is well outside the evacuation zone, the studio and producers said it'd be prudent to hold the premiere on another day.
"In light of the ongoing, active fires being battled in the area, Paramount Pictures and Skydance have canceled tonight's Los Angeles premiere of Terminator: Dark Fate," the studio said in a statement. "We will be donating food intended for the after-party to the American Red Cross, which is serving those affected by the fires."
David K. Li
David K. Li is a breaking news reporter for NBC News.