Reinforcements are also expected to arrive from the neighbouring states of Arizona and Nevada.

More than 11,000 firefighters were still battling catastrophic wildfires in California that have killed at least 18 people, destroyed 2,000 homes and forced tens of thousands into shelters.

The sky over the second largest city in the United States, Los Angeles, was painted an eerie hue of orange as a thick pall of smoke from fires burning over 200,000 hectares (500,000 acres) of the state blocked out the sun.

Giant plumes of smoke stretched miles up into the sky and were visible from space as up to 50,000 more residents of mountainous areas east of here fled their homes as flames exploded through fire cordons.

"This may well be the worst disaster the state has faced," outgoing California Governor Gray Davis said of the 14 fires, many of which are now thought to have been sparked by arsonists.

"I expect the cost in the next few days to near two billion dollars," he said, adding that the figure included loss of infrastructure, relief and firefighting efforts.

The governor's Office of Emergency Services said the fires had burned at least 217,200 hectares (543,000 acres) in the south of the most populous US state and had killed at least 16 people in California.

A further two died in Mexico after the flames jumped the international border at San Diego, and officials in California said more dead were certain to be found in the disaster zones when the flames clear.

Nine major infernos were blazing around the southern city of San Diego, in Los Angeles' suburban San Fernando Valley and in a popular mountain area in San Bernardino County, 80 kilometers (50 miles) east of here.

"It's a rolling disaster that's just growing in size, its overwhelming," said Patty Roberts of the OES, which is coordinating fire data.

But fire officials in San Bernardino County ordered a new wave of mandatory evacuations of up to 50,000 from mountain-top towns the eight-day-old blaze exploded into new territory towards the popular big bear vacation area.

That fire has chewed up 33,200 hectares (83,000 acres) of forestland, with officials in the area that worse was likely to come.

And thousands of residents near San Diego were also ordered out of their homes too as three major fires chewed up around 120,000 hectares (300,000 acres) around the fire besieged city of 1.2 million people.