LOS ANGELES (AP) — Powerful gusts pushed flames from a wildfire through Southern California canyons early Thursday, one of several blazes that burned near homes and forced residents to flee amid elevated fire risk for most of the region that prompted utilities to cut off power to hundreds of thousands.

The biggest blaze, in Orange County's Silverado Canyon, began late Wednesday as a house fire that quickly spread to tinder-dry brush as gusts topped 70 mph (113 kph).

It exploded in size throughout the night and as the sun came up, an enormous plume of smoke was visible for miles.

Firefighters struggled in steep terrain amid unpredictable Santa Ana winds. Orange County Fire Authority Captain Thanh Nguyen said crews were scrambling to stay ahead of flames that jumped major roads.

“We’ve seen the wind change also drastically, so that’s what we’re telling all our personnel to be aware of — that constantly changing wind,” he told CBS LA TV.

Evacuations were ordered for several canyon and foothill neighborhoods near the city of Lake Forest and residents of other nearby areas were told to be ready to get out.

It was not immediately known how many people were affected or if any homes were damaged in the 6-square-mile (16-square-kilometer) conflagration. There was no containment of the fire.

Numerous studies have linked bigger wildfires in America to climate change from the burning of coal, oil and gas. Scientists have said climate change has made California much drier, meaning trees and other plants are more flammable.

The Bond Fire about 50 miles (80 kilometers) southeast of Los Angeles is burning near the same area of October’s Silverado Fire, which forced tens of thousands of people to evacuate.

Ryan Kayrell fled the October fire with his wife and two young children. But the family stayed at their home in the community of Foothill Ranch on Thursday morning even though it lies in a very smoky mandatory evacuation zone. The family's bags were packed as they waited to see which way the flames move, Kayrell said,

“A lot of the hillside immediately behind my house is already burned, so we're hoping that's a buffer. Which isn’t to say that there’s no danger. The concern is that embers could fly into the neighborhood,” Kayrell said. “If there are fire trucks on our street, we're going.”

The new blaze broke out as Southern California utilities cut the power to tens of thousands of customers to avoid the threat of wildfires during the notorious Santa Anas.

Red flag warnings of extreme fire danger through Saturday were in place because of low humidity, bone-dry brush and the winds, which sweep down from the interior, the National Weather Service said.

Utilities in the populous region began cutting power Wednesday to customers as a precaution to prevent gusts from blowing tree limbs into electrical equipment or knocking down power lines, which have sparked devastating wildfires in recent years.

Southern California Edison cut power to about 15,000 homes and businesses by late Wednesday night and was considering de-energizing lines serving about 271,000 customers in seven counties throughout the windy period, which could last into Saturday.

It was one of the utility’s largest precautionary blackouts.

San Diego Gas & Electric pulled the plug on about 24,000 customers by Wednesday night with another 73,000 in the crosshairs.

“We recognize losing power is disruptive, and we sincerely thank our customers for their patience and understanding,” the utility said.

Evacuations were ordered when a small wildfire broke out near the rural community of Nuevo in Riverside County, about 50 miles (80 kilometers) to the east of the Bond Fire.

And to the south, small blaze in San Diego County threatened about 200 homes and prompted evacuations before firefighters managed to contain 50 percent of it. At least one structure was destroyed and six others were damaged, according to 10 News San Diego.

California already has experienced its worst-ever year for wildfires. More than 6,500 square miles (16,835 square kilometers) have been scorched, a total larger than the combined area of Connecticut and Rhode Island. At least 31 people have been killed and 10,500 homes and other structures damaged or destroyed.

The latest fire threat comes as much of California plunges deeper into drought. Virtually all of Northern California is in severe or extreme drought while nearly all of Southern California is abnormally dry or worse.

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Associated Press reporter Amy Taxin contributed from Orange County, California.