The fire grew by more than 50,000 acres during the day, triggering new evacuation orders for about 5,000 county residents, including those east of Mission Canyon and north of Highway 192. An additional 30,000 residents west of Mission Canyon to Highway 154 and south of Highway 192 to the county line were told to prepare to leave.
As the fire grew Sunday, containment dropped from 15% to 10%, authorities said.
The blaze has destroyed 524 structures and damaged 135 in the city of Ventura. In the unincorporated areas of Ventura County, 266 structures have been destroyed, while 56 were damaged. The fire consumed six structures on Sunday in beach town of Carpinteria, authorities said.
Santa Ana winds, aided by extremely low humidity, pushed the Ventura County fire over the Santa Barbara County line Saturday night. The winds that bedeviled fire crews from San Diego to Ojai last week were gusting at speeds of up to 35 mph, fire officials said.
Their greatest concern was for Carpinteria. The fire was moving west above the city in an area of very dry vegetation that hasn't burned in about 100 years, said Steve Swindle, spokesman for the Ventura County Fire Department.
"The fuels in there are thick and they're dead so they're very receptive to fire," Swindle said.
Fire officials feared that if the fire moves into nearby creek beds, it might create a chimney-like effect, sending the flames roaring along the creek's path.
Firefighters on Sunday morning were making a stand at a cluster of homes on Shepard Mesa Road where flames threatened to sweep through the area, according to the Santa Barbara County Fire Department.
The department posted a photo of one home burning on Gobernador Canyon Road. It's unclear whether other structures were lost.
Crews were cutting lines outside the city in an effort to keep flames from further encroachment and "contingency strike teams" were dispatched throughout Carpinteria in case the blaze manages to cross fire lines, said Newport Beach firefighter Jude Olivas, a spokesman for the Thomas fire response.
By midmorning Sunday, the fire was burning the Camino Cielo mountain range and approaching Cate School, a Carpinteria boarding school under mandatory evacuation. On its website, the school said it would remain closed until after winter break, according to fire officials.
Southern California Edison officials said Sunday that up to 85,000 customers in Santa Barbara County were without power.
The Santa Barbara Zoo was closed to the public Sunday, and its 500 animals were confined to their night quarters. The zoo was outside the evacuation area and not in immediate danger, but there was smoke and ash on the 30-acre property.
"We drill for and are prepared for emergencies," zoo director Nancy McToldridge said in a Facebook post. "We are taking all precautions to ensure the safety of our animals and our staff."
The animal care staff was providing "enrichment," including toys, treats and puzzles, to prevent the zoo residents from becoming bored inside, said director of marketing Dean Noble.
"The gorillas like music," Noble said.
Even as the Thomas fire surged, the approximately 8,500 firefighters battling the six wildfires across Southern California were making progress.
Firefighters had a successful day Saturday battling flames on the southern edge of the Thomas fire — working toward the coast as well as parts of Ojai — thanks to wind conditions and crews' ability to improve the fire lines they had established, according to Bill Murphy, a spokesman for the California Department of Forestry and Fire Protection, or Cal Fire.
The Thomas fire has forced 88,000 people to flee their homes. Official estimates have put the cost of combating the fire at $25 million.
Across Ventura County, blackened hillsides and charred palm trees with only their trunks remaining have become a common sight.
By Sunday morning, evacuations had been lifted for most of the city of Ventura and for Santa Paula.
The cause of the fire, which began Monday east of Highway 150 near Thomas Aquinas College, is under investigation.
During a news conference at the Ventura County Fairgrounds, Gov. Jerry Brown said climate change may exacerbate the weather conditions that caused the wildfires to explode. He expressed sympathy for residents who had lost their homes and animals, saying the fires were horrific and a "terrible tragedy for so many people."
"This could be something that happens every year or every few years," he said. "We're about to have a firefighting Christmas."
In Los Angeles County, firefighters made progress on blazes in Sylmar, Santa Clarita and Bel-Air. The Creek fire was 90% contained, and the Rye fire was 90% contained as of Sunday morning. The Skirball fire was 75% contained.
In northern San Diego County, the Lilac fire, which was 60% contained, had burned 4,100 acres and destroyed 182 structures along the Highway 76 corridor that stretches west from the 15 Freeway through Bonsall and Fallbrook. Officials cautioned that dry, swirling Santa Ana winds could kick up embers that might start new fires.
At least 46 horses were killed at a thoroughbred training facility, San Luis Rey Downs in Bonsall, where an estimated 450 were stabled. Mike Marten, a spokesman for the California Horse Racing Board, said Saturday that a small number of horses had escaped to the wilderness through a fence that was knocked down and had yet to be found.
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