UPDATE 10:35 a.m.: Los Angeles Mayor Eric Garcetti says at least four and possibly six homes have been destroyed by a wildfire in the city's Bel Air area.
The fire erupted before dawn Wednesday in Sepulveda Pass, a major commuter route between the west side of Los Angeles and the San Fernando Valley to the north.
The fire burned up hillsides on the east side of the pass into expensive neighborhoods that are now under evacuation orders.
The mayor says the fire is now 150 acres with zero containment.
Some 500 firefighters are battling the fire along with water-dropping helicopters and airplanes laying down streams of fire retardant.
The dangerous Santa Ana winds that have fanned fires across Southern California this week have diminished over the new LA fire but conditions are very dry, with just 9 percent relative humidity.
UPDATE 9:15 a.m.: President Donald Trump says his thoughts and prayers "are with everyone" in the path of California's latest wildfires.
Trump in a tweet is also encouraging everyone "to heed the advice and orders of local and state officials" and thanking first responders for their "incredible work!"
Wind-driven fires have raced through California communities for the second time in two months, leaving hundreds of homes feared lost and uprooting tens of thousands of people.
The most damaging fire is in Ventura County northwest of Los Angeles, where more than 100 square miles (259 sq. kilometers) and numerous homes have burned.
Deadly fires tore through Northern California earlier this year.
UPDATE 9:08 a.m.: The Thomas Fire, the biggest and most destructive of several wildfires burning in Southern California, has scorched more than 65,000 acres according to CAL FIRE.
State fire authorities say the fire burning in Ventura County about 60 miles northwest of Los Angeles is also considered a threat to 12,000 structures Wednesday.
Dozens of homes have burned since the fire erupted Monday amid fierce Santa Ana winds.
A new fire burning among ridges and canyons on the west side of Los Angeles has also burned several homes while snarling morning commuter traffic.
UPDATE 7:28 a.m.: Mandatory evacuations have been ordered in an exclusive ridge-top neighborhood in Los Angeles as a dangerous new wildfire burns in Southern California.
The fire erupted before dawn Wednesday on the east side of Sepulveda Pass, which carries heavily traveled Interstate 405 through the Santa Monica Mountains on the city's western side.
Helicopters are making water drops and more than 200 firefighters are battling flames close to homes.
In addition to the mandatory evacuations, Los Angeles Fire Department spokeswoman Margaret Stewart says a wider area on the east side of the pass has been advised to get ready in case of evacuation orders.
(AP) - The same vicious winds that have made this week's Southern California wildfires so destructive are also making the firefight itself more difficult.
The water-dropping planes and helicopters essential to fighting massive fires have been mostly grounded because it's too dangerous to fly in the strong gusts.
Commanders hoped to have them back in the air on Wednesday morning, but all indications are the winds will be whipping then too.
The blazes brought evacuation orders for nearly 200,000 people, destroyed nearly 200 homes and have remained mostly out control.
The largest and most destructive of the blazes, an 85-square-mile wildfire in Ventura County northwest of Los Angeles, had nearly reached the Pacific Ocean on Tuesday night after starting 30 miles inland a day earlier.
A brush fire has also erupted on the east side of Los Angeles along Interstate 405 in Sepulveda Pass.
Fire Department spokesman Margaret Stewart says the fire was reported at 4:52 a.m. Wednesday and is burning uphill, driven by topography rather than winds.
Stewart says 47 firefighters are on the scene, setting up protection for homes at the top of the steep slopes. Two firefighting helicopters have been assigned.
Sepulveda Pass carries heavily traveled Interstate 405 through the Santa Monica Mountains between the western neighborhoods of Los Angeles and the San Fernando Valley to the north.