The blaze moved south toward the Getty Center and Mount St. Mary's College, but both were "well-protected by a large number of firefighters," Humphrey said.
The Getty Center, which houses one of the world's richest art collections and a research institute, was closed Thursday as a precaution, and the college canceled morning classes due to the blaze.
All lanes of the San Diego Freeway were shut down in both directions for about four hours. The four-mile long stretch of the heavily traveled freeway reopened just before the morning rush.
Authorities warned that the freeway could be closed again at any time if the fire flares up, and several onramps in the area remained closed.
The cause of the fire was not known. No structures had burned and no one was injured, Humphrey said.
More than 500 firefighters helped by 10 water-dropping helicopters were taking on the blaze, authorities said.
Despite its quick growth, the hot, dry winds that brought the fire's initial surge were diminishing, very little open flame was visible from television news helicopters and firefighters were gaining ground.
"The weather is cooperating right now," Deputy Chief Donald Frazeur said at a news conference. "If the weather doesn't pick up like is predicted we should be able to contain this without any problem."
Winds were blowing only about 5-10 mph, but were expected to pick up later in the morning.
Authorities told residents in the Brentwood area they may need to evacuate, and centers were set up at the Stephen Wise Temple and the Veteran's Administration Hospital in Westwood for any sick or elderly people who needed to evacuate.
Some residents loaded computers and collectibles into cars and headed out of the exclusive mountain area of Brentwood.
"This is really surreal," Mort Overlander told KTLA-TV as he fled his home. "It's like out of a movie or something. Especially coming down the hill, it's just unbelievable."