California fires bear down on exclusive Los Angeles suburbs

Part of Murdoch's Moraga Bel Air vineyard, where the 86-year-old Australian has a home, has been destroyed by fire, and it is one of a number of properties affected by a mandatory evacuation order, issued by emergency services today.

The fires have also closed one of America's busiest freeways - the traffic-choked 405 - with video emerging of one of the four fires reaching the edge of the freeway.

The pre-dawn sky of Los Angeles was lit bright orange with fire as traffic moved at a slow, silent crawl past the inferno until police made the decision to close a 15km stretch of the freeway because of the risk.

In total around 34,000 hectares are now burning and the fires, fuelled by the dry Santa Ana winds, have burned hundreds of buildings in Los Angeles county and neighbouring Ventura county.

More than 10,000 people have evacuated their homes already and an additional 150,000 people are now affected by evacuation orders.

According to emergency services there are 43,000 homes without power with fires burning along power transmission lines, threatening further outages.

More than 80 schools have been closed.

There are four major fire fronts, with the smallest one - the Skirball Fire, which is around 20 hectres in size - touching the perimeter of one of LA's wealthiest enclaves, the iconic Bel Air.

The fire, named for its proximity to the Skirball Cultural Centre, is the fire which has forced the closure of the 405 freeway; the Skirball fire is also close to the iconic Getty Centre.

It is the Skirball fire which is threatening the the Murdoch vineyard and estate; firefighters broke through the property gates today to deal with a fire in part of the vineyards and three water helicopter drops have been made in the affected area.

"The situation at Moraga Bel Air is very fluid at the moment," Rupert Murdoch said in a statement.

"We are monitoring the situation as closely as we can and are grateful to the efforts of all the first responders," Murdoch said.

"Some of our neighbours have suffered heavy losses and our thoughts and prayers are with them at this difficult time."

The other three fire fronts are the Creek Fire and Rye Fire in Los Angeles county, and the Thomas Fire in Ventura county, which is to the north of the city.

The largest of the four is the Thomas Fire in Ventura County, burning at least 26,000 hectares; it has destroyed at least 150 buildings in a city of approximately 100,000 people.

Almost 40,000 people in Ventura have been told to evacuate and more than 12,000 buildings are "under threat", officials said.

The second largest fire is the Creek Fire in northern Los Angeles, which is almost 5000 hectares in size; the third is the Rye Fire, which is almost 3000 hectares in size.

The fires are burning with unusual speed, fuelled by dry weather conditions and unusually fierce Santa Ana winds.

To illustrate the speed of its spread, Ventura's Vista del Mar Hospital - an 82-bed mental health facility - was burned just two hours after it was evacuated.

California's governor Jerry Brown declared a state of emergency in the state, insisting residents obey evacuation orders.

"It is critical residents stay ready and evacuate immediately if told to do so," he said.

The sentiment was echoed by LA's city mayor Eric Garcetti, who said: "We have lost structures, we have not lost lives.

"Do not wait, leave your homes," Garcetti said.

The Santa Ana winds are dry desert winds which push towards the west, from California's inland deserts towards the coast; emergency services are expecting the winds to worsen in the next two days.

Los Angeles police chief Charlie Beck said the county was facing a "a multi-day event", warning that worsening wind conditions could amplify the threat in the coming days.???

The National Weather Service has issued a "critical" weather warning for the Los Angeles and Ventura counties, saying that "fire weather conditions will continue" for the next day at least.

The conditions were described as "dangerous high-end critical to extremely critical".

The NWS also issued a high wind warning, a critical factor in the fast spread of the fires; there was "potential for very rapid fire growth" and "extreme fire behaviour," the warning said.