The blaze, which was reported at 4:52 a.m. Wednesday on the east side of the San Diego (405) Freeway near Mulholland Drive and prompted a morning rush hour closure of the freeway in the Sepulveda Pass, was estimated to have scorched at least 475 acres, Hogan said. The four-day old Thomas Fire had burned 115,000 acres and destroyed 439 buildings, damaging 85 others.
The area battled gridlocked heavy traffic as ash and smoke churned over the smoldering hillside.
Out-of-control wildfires are raging in and near Los Angeles.
Other agencies assisting include the U.S. Forest Service, Los Angeles County Fire Department and Cal Fire.
"What you'll see today is more resources up there making an aggressive attack, doing everything we can to try to get our arms all the way around it ... to work towards full containment", Hogan said.
The "Skirball" fire ignited before 1300 GMT and quickly grew to engulf some 150 acres, with forecasters predicting that 40kph winds could cause further spreading, threatening multi-million dollar homes and the acclaimed Getty Center museum.
Officials said the strong winds fanning the fires are forecast to last through Saturday, making for extremely unsafe conditions.
A cloud of black smoke was creeping across the city with a large, dark column rising into the air, leaving authorities concerned about the poor quality of air that was unbreathable in some places.
Television footage showed the Bel-Air neighborhood home to celebrities and billionaires, where both entrepreneur Elon Musk and pop superstar Beyonce own property.
The fire was burning in the same general area as the devastating Bel-Air Fire of 1961.
All Santa Monica-Malibu Los Angeles Unified School District schools will be closed Wednesday due to the fire.
LAFD Chief Ralph Terrazas noted that red flag conditions are expected to remain in effect at least through Friday, with gusting Santa Ana winds presenting a continuing danger of rapidly spreading blazes.
The singer Lionel Richie cancelled a concert to help his ex-wife flee the area, while comedian Chelsea Handler and designer Adrienne Maloof were among those tweeting that they had to evacuate. "Praying for [people] up in those mountains, LA County and myself this morning". While the freeway closures were in the name of safety, one negative result was a massive gridlock in one of Los Angeles' most congested and busy areas.
But power lines arcing in strong winds, or collapsing when trees crash into them, have triggered many of California's most destructive fires.