The so-called Skirball Fire, which erupted early on Wednesday (local time) as the latest in a rash of major blazes fuelled by hot, dry Santa Ana winds, had burned about 60ha near large estates in the Bel-Air neighborhood of Los Angeles by early afternoon.
Firefighters battled to save multimillion-dollar homes in the path of the flames, which also forced the closure of the San Diego (405) Freeway in both directions, and warned that if the winds picked up again in the evening the situation could become even more dire.
"It would be safe to say there are hundreds of homes in the area," said Brian Humphrey, spokesman for the Los Angeles Fire Department.
Murdoch's winery, Moraga Vineyards, was evacuated on Wednesday morning as the fire descended on the grounds, a spokeswoman said. Later a structure on the property was seen on fire as a water-dropping helicopter tried to extinguish the flames.
The new fire also prompted the nearby Getty Center museum to close the doors at its hilltop campus to prevent damage to its world-class art collection.
The Skirball Fire in the area south of scenic Mulholland Drive and north of Sunset Boulevard is just one of several major out-of-control brush fires that have sprung up in Southern California since Monday, when Santa Ana wind conditions set in.
In Ventura, some 80km northwest of Los Angeles, more than 1000 firefighters battled the largest, the Thomas Fire, which has already destroyed more than 150 homes and threatened thousands more.
California Governor Jerry Brown declared a state of emergency on Tuesday, freeing state funds and resources to assist firefighters. The Federal Emergency Management Agency said it approved grants to help cover the cost of emergency work for the Thomas Fire and two others.
US President Donald Trump said on Wednesday his thoughts and prayers were with everyone in the path of the wildfires.
"I encourage everyone to heed the advice and orders of local and state officials," Trump wrote on Twitter. "THANK YOU to all First Responders for your incredible work."
Although no casualties have been reported, the fires have forced mass evacuations, cancellation of classes at dozens of schools and resulted in the loss of power at more than 250,000 homes in Ventura County.
In the San Fernando Valley north of Los Angeles, the Creek Fire destroyed at least 30 homes, blackened more than 11,000 acres and forced the evacuation of 2,500 homes and a convalescent center north of Interstate 210 on Tuesday.
Three firefighters were injured and hospitalized in stable condition, the Los Angeles Fire Department said.
The Santa Ana winds, which blow westward from the California desert, were forecast to top out at 115kmh on Wednesday and remain strong through the week.
