Firefighters were bracing for more heavy winds as they battled on Tuesday to contain two wildfires blazing north of Los Angeles that have left one person dead and forced thousands to flee.
More than 6,000 hectares (15,000 acres) have been scorched by twin blazes burning near San Fernando and Porter Ranch on the northern outskirts of Los Angeles, which have roared through tinder-dry countryside in 48 hours.
One person has been killed and at least 4,000 people are estimated to have been evacuated, prompting California Governor Arnold Schwarzenegger to declare a state of emergency in the region on Monday.
On Tuesday, firefighters said the fire in Porter Ranch had almost doubled in size to 4,000 acres 9,900 acres and remained uncontained.
"We are prepared for whatever Mother Nature throws at us," Los Angeles Fire Department spokesman Brian Humphrey said. "It depends on the winds. In this situation, wind is king. The winds could even be benevolent."
Schwarzenegger, too, pointed to the Santa Ana winds that rake the state as a key culprit fanning the flames.
"That is what makes this so dangerous," the governor said at a command center.
"We're basically getting the perfect storm. Very strong (winds), low humidity, and heat. Those are the three elements that create those kind of fires and makes them get out of control."
The National Weather Service has predicted that the winds -- packing speeds of up to 70 miles per hour (113 kph) -- will continue gusting until on Wednesday.
Across southern California, wildfires in recent days have consumed a total of 26,000 acres (about 10,000 hectares) and 64 buildings and structures, Schwarzenegger said.
At the other major fire blazing 15 miles (24 kilometers) to the east near San Fernando, flames had destroyed around 5,000 acres (2,000 hectares) and gutted 38 mobile homes, officials said.
But a lull in overnight winds allowed firefighters to gain the upper hand over the blaze, which was 70 per cent contained, up from only five per cent late on Monday, Los Angeles County Fire Captain Mark Savage said.
"So far, so good, but we're not done yet," Savage said.
Authorities say 1,200 people have been evacuated from the two fires but several more neighborhoods were ordered to leave their homes later on Monday and the number of evacuees may rise.
The exact causes of the two fires are unknown. They are among several burning across southern California which have broken out since Sunday.
The biggest of the other fires near the US Marine Corps' sprawling Camp Pendleton base outside San Diego, was close to being brought under control. Some 1,200 hectares (3,000 acres) have gone up in flames, but evacuation orders for more than 1,000 homes have been lifted.
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.
The latest fires comes roughly one year after devastating wildfires that were among the worst in California history left eight people dead, destroyed 2,000 homes, displaced 640,000 people and caused one billion dollars in damage.
In June and July this year, a series of about 2,000 fires raged across the state, scorching some 900,000 acres (3,500 square kilometers) of land, according to officials.