Los Angeles - After four days of widespread devastation, California firefighters on Tuesday had three large fires under control, and evacuated residents returned to find hundreds of homes gutted by the flames.

Aided by lighter winds, firefighters in southern California were gaining the upper hand on three wildfires that have devastated the region. They were hopeful of containing the blazes by mid-week.

The fires have destroyed hundreds of homes since Thursday, including 500 mobile homes in Sylmar, east of Los Angeles. More than 100 homes in the luxurious celebrity enclave of Montecito, north-west of Los Angeles, also went up in flames while 120 homes in Yorba Linda south of Los Angeles were destroyed.

Authorities said late Tuesday that the Montecito fire had been caused by teenagers holding a bonfire party. The youngsters apparently failed to completely douse the flames late on November 12, and the strong winds that began the next morning stirred up the embers and ignited the catastrophic fire.

According to figures released Tuesday by Cal Fire and the National Inter-agency Fire Centre, the Triangle Complex fire had burnt 11,600 hectares and 155 structures and was 75 per cent contained. The Sayre fire had burnt 4,400 hectares and 604 structures and was 70 per cent contained. The Tea fire had burnt 800 hectares and 210 structures and was 100 per cent contained.

More than 5,800 firefighters were still mopping up hotspots to prevent fires from reigniting. But with the winds that fanned the flames dying down, fire chiefs were confident enough to allow most of the 50,000 evacuees to return home.

"The firefight is over," said Marlene Heisey, an information officer with the California Department of Forestry and Fire Protection.

Fire officials said they had not yet determined the cause of any of the fires but had ruled out natural causes in the case of Montecito's Tea fire. The fires were fanned by seasonal Santa Ana winds that gust in from the eastern desert, blowing warm, dry air at more than 110 kilometres per hour, launching burning embers from tree to tree and house to house.

California Governor Arnold Schwarzenegger declared a state of emergency in five counties and called for tougher standards for mobile-home construction, after the extent of destruction at the mobile-home park became clear.

He asked the Bush administration to declare Southern California a federal disaster site and sought disaster loans for the counties of Los Angeles, Orange, Riverside, Santa Barbara and San Bernardino, where he said many of the residents affected by the fires - particularly mobile-home owners - lacked insurance or were inadequately insured.

The latest round of fires exacerbated what had already been a disastrous wildfire year in California, where more than 624,000 hectares had burnt before the latest wildfires, compared to 608,000 hectares last year. (dpa)