LOS ANGELES, USA - FIREFIGHTERS were battling wildfires across California on Sunday that have gutted hundreds of homes and forced thousands to flee, as investigators began a painstaking search through smoldering rubble for possible victims.

Around 800 residences - ranging from multi-million-dollar mansions to modest prefabricated mobile homes - have been razed by several devastating infernos that have erupted through the region since Thursday.

At least 50,000 evacuation orders have been issued and nearly 8,900 hectares have been destroyed in the blazes, which have stretched from Santa Barbara to south-east of Los Angeles.

Urban search and rescue teams including cadaver dogs were sent into the ground zero of the Los Angeles fire, a mobile home park in the northern suburb of Sylmar where more than 500 residences were incinerated.

Los Angeles Police Department deputy chief Michael Moore told a press briefing at 12.30pm (4.30am Singapore time) that approximately 30 per cent of the devastated mobile home park had been searched on Sunday and no human remains had been found.

'At this point we have no missing persons, no reported missing persons or no evidence to tell us that there is loss of life,' Mr Moore said. 'It is an exceedingly difficult task. There's still much work ahead of us.'

Los Angeles fire officials meanwhile said progress had been made overnight on Saturday in tackling the 3,844ha fire, with 30 per cent containment reached after a lull in fierce local winds.

'The winds have settled down so we're looking to get a handle on this fire this afternoon,' Los Angeles fire captain Bill Wick told local television.

The cause of the fire remains unknown.

California Governor Arnold Schwarzenegger, who has declared a state of emergency in the fire affected areas, told a briefing on Sunday authorities were dealing with a 'perfect storm'.

'With all these fires all over, this is usually what happens at this time of the year, when we have the perfect storm, which means basically we have high winds, high temperatures and very very dry,' Mr Schwarzenegger said.

A total of around 3,700 firefighters, using helicopters, bulldozers and engines, were battling fires across the state.

Meanwhile, firefighters in Orange County, south of Los Angeles, were battling a 4,230ha complex of fires which erupted near Yorba Linda and Corona on Saturday, fanned by notorious Santa Ana Winds.

The fire had destroyed at least 104 residences and eventually prompted as many as 40,000 evacuations in three counties.

Fire officials said they had struggled to keep pace with the fires as they swept through tinder-dry brush and chaparral.

'We just started losing homes. We didn't have enough units,' said Mr Mickey Hansen, a safety officer with the Orange County Fire Authority. 'There were just so many fires. There wasn't enough (resources) to go around.'

Meanwhile, hundreds of firefighters were making steady progress against the fire which tore through the millionaires' playground of Montecito after erupting on Thursday.

Some 210 residences had been gutted by the fire, which has burned around 785 ha and was 75 per cent contained.

California is frequently hit by scorching wildfires due to its dry climate, Santa Ana winds and recent housing booms which have seen housing spread rapidly into rural and densely forested areas.

Only just over a year ago, California suffered devastation from wildfires among the worst in its history that left eight people dead, gutted 2,000 homes, displaced 640,000 people and caused US$1 billion (S$1.5 billion) in damage.

In June and July this year, a series of about 2,000 fires raged across the state, scorching some 364,230ha of land.