SAN FRANCISCO — High winds and brittle conditions fueled fast-growing wildfires across California as utilities began restoring power to more than 200,000 homes and business that went dark in an effort to prevent blazes.

In Sonoma County, 75 miles north of San Francisco, the fast-growing Kincade Fire flared up late Wednesday and within hours covered more than 15 square miles. The National Weather Service reported wind gusts of up to 76 mph, prompting evacuation orders to remain in place for about 2,000 people in several communities.

"Leave immediately if you are in these locations," the Sonoma County Sheriff's Office warned, citing an "extraordinary threat to life or property."

As of 7 p.m. local time, Cal Fire said 49 buildings had been destroyed and that structures and power lines were threatened by the blaze. More than 1,300 firefighters were on the scene, backed by more than 100 engines,17 air tankers and 25 bulldozers.

The blaze grew to 16,000 acres Thursday evening, Cal Fire incident commander Mike Parkes said at a news conference. Containment was at 5% and no injuries had been reported.

A smaller but fast-moving blaze also broke out in Marin County, just north of San Francisco. The fire had charred 58 acres and forced the closure of Highway 1, the iconic Pacific Coast Highway. Near a section of the highway in San Mateo County, a 75-acre blaze sparked late Thursday.

A pair of fires near Santa Clarita in Los Angeles County force 50K evacuations

Southern California was not immune to the fire conditions, fires, or outages.

A wildfire broke out Thursday afternoon in Canyon Country in the northern section of Los Angeles County, where it was threatening homes. The smoke plume was visible across the Los Angeles basin.

The Tick Fire, driven by scorching winds and temperatures well above 90 degrees, had consumed 3,950 acres and was nearing the edges of upscale housing tracts. Four air tankers had been requested in addition to water-dropping helicopters, the Los Angeles County Fire Department said.

A few miles northeast near Castaic, a 20-acre brush fire temporarily closed part of Interstate 5 in the afternoon. It was contained by Thursday night, said Los Angeles County Fire Chief Daryl Osby.

About 50,000 people were ordered to evacuate their homes outside Los Angeles, mostly around Santa Clarita.

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A fire in San Bernardino County, about 60 miles east of Los Angeles, was only about 100 acres, but evacuations were ordered early Thursday. Citing the outages and fire, California State University, San Bernardino canceled classes Thursday.

The San Bernardino County Fire Department warned the blaze, known as the Old Water Fire, had the "potential for large growth."

Southern California Edison cuts off power to nearly 31K customers

Southern California Edison had cut power to about 31,000 customers and warned that 386,000 more could see preemptive outages.

The bulk of the power outages, however, affected at least 500,000 people, were in central and northern California, where Pacific Gas & Electric has been warning for days that high winds forecast for the state could result in preemptive power shutoffs. Residents should be ready to be without power for 48 hours or more, the company said.

PG&E had restored power for about 150,000 customers by Thursday night, and said it expects all customers to have power by no later than Friday night.

Sonoma County Sheriff Mark Essick said the blackouts had not hampered efforts to inform people they had leave because authorities had learned to communicate through multiple platforms after previous blazes – especially the devastating Wine Country fires two years ago.

But he lamented that some residents still chose to stay despite the obvious danger.

“I know more people feel better prepared than they were two years ago,'' Essick said. "Many people have taken the time to prepare kits, prepare their homes for wildfire, but this is not the time to stay. This is the time to go. Please heed the evacuation order.’’

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The latest waves of outages come two weeks after gusty winds, high temperatures and parched conditions forced PG&E to shut off power to 2 million people, many for several days. That preemptive outage, or Public Safety Power Shutoff, fueled outrage from many residents, but PG&E defends the outages as crucial to the safety of its customers.

As part of a preliminary investigation, PG&E filed a report that one of its transmission lines went out in the Geysers area where the Kincade Fire burned Wednesday night. The utility did not preemptively shut off that transmission tower, a press release said.

Santa Ana winds in weekend forecast

The weather service in Los Angeles warned that due to the forecast of gusty Santa Ana winds both Thursday and Friday, there is "the potential for rapid fire growth and extreme fire behavior if ignition occurs."

Warm and dry conditions are also expected to persist in Northern California on Friday, forecasters said. Late Saturday through early Monday could also bring "the strongest wind event so far this fall," according to the weather service, possibly bringing more preemptive shutoffs.

PG&E acknowledged some of the same subscribers could be in for another blackout later in the weekend: "Customers should prepare by fully charging their communications, medical and other devices while the power remains on,'' PG&E said.

Contributing: Chris Woodyard, USA TODAY; The Associated Press.