GEYSERVILLE, Calif. (AP) — Fast-growing fires throughout California forced thousands of people to evacuate their homes Thursday as dry winds and high heat fed both the flames and fears in a state still jittery from devastating wildfires in the last two years.

Officials said they did not yet know how many homes had burned and that no immediate injuries were reported. It's not clear how any of the blazes began.

In Northern California wine country, authorities ordered 2,000 people to evacuate as a wildfire exploded to more than 15 square miles (39 square kilometers), whipped up by the strong winds that prompted utilities statewide to impose blackouts to prevent such fires from igniting.

Officials ordered an evacuation of the entire community of Geyserville, home to about 900 people and a popular stop for wine country tourists, along with nearby residents. The blaze threatened some of the area's famed wineries and the River Rock Casino as the blaze raged on the outskirts of town.

In Southern California, a wall of flame rolled along the parched foothills north of Los Angeles, where thousands of homes have sprung up in recent decades.

Officials told people to flee along a mileslong stretch of Santa Clarita, where the fire quickly consumed more than a square mile (2.5 square kilometers) of dry brush and threatened homes. Winds gusting to about 40 mph (65 kph) pushed the blaze as enormous plumes of smoke visible for miles covered neighborhoods.

A second fire broke out about 10 miles (16 kilometers) away, racing up a hillside to the edge of a neighborhood in Castaic and burning at least two houses. People used hoses to try to protect their properties.

Until now, the focus of California's wildfire season had been on power outages that utilities said were necessary to stop high winds over the coming days from toppling power lines and starting fires. But the season kicked into higher gear Thursday with the arrival of raging fires and the need to quickly escape them.

A series of deadly blazes tore through the same area in Northern California wine country two years ago, killing 44 people.

Among those fleeing Geyserville was 81-year-old Harry Bosworth, who awoke before sunrise to find a firetruck and firefighters in his driveway. As he and his wife drove off, flames surrounded their driveway and their barn caught fire.

"I could see the fire coming, so we got the heck out of there," Bosworth said after escaping to his daughter's house in the neighboring town of Healdsburg.

Julia Jackson of Geyserville-based Jackson Family Wines, which owns more than 40 wine labels and thousands of acres of vineyards, posted on Instagram that her home was "burnt down to the ground."

"Stuff is just stuff. Thank God I'm alive," she wrote. Jackson, who founded a climate change conference, said such fires are why she is doing the work.

Another Geyserville evacuee, Isaac Hale, said he woke up to the sound of authorities ordering him out.

"The highway patrol showed up banging on the door, ordering everyone to evacuate because the fire was so close," Hale said, seated on top of his SUV near a road closure checkpoint. "The fire, it just spread so fast."

It started Wednesday night near the Geysers, the world's largest geothermal field, where nearly two dozen power plants draw steam from more than 350 mountain wells to create electricity, California Department Of Forestry And Fire Protection incident commander Mike Parkes said.

It was fueled overnight by 76 mph (112 kph) winds in rugged terrain that was hard to reach, he said. Some people were refusing to leave despite the danger, Sonoma County Sheriff Mark Essick said.

"Please heed our evacuation order," he said in a televised news conference. "We really need to be able to fight the fire, rather than worrying about rescuing you."

The fire raged amid rolling blackouts instituted after utility electrical equipment was blamed for setting several blazes in recent years that killed scores of people and burned thousands of homes.

The state's largest electric utility, Pacific Gas & Electric, filed for bankruptcy protection in January as it faced billions of dollars in damages from such wildfires. The investor-owned energy company has set aside billions for insurers and wildfire victims while facing a public backlash over its handling of the outages.

PG&E spokesman Paul Doherty said parts of Geyserville lost power as scheduled Wednesday. The company's outages are affecting half a million people or nearly 180,000 customers.

In Southern California, hot and dry Santa Ana winds led Southern California Edison to cut power to more than 27,000 customers. It was considering additional power cuts to more than 386,000 customers.

The latest outages come two weeks after PG&E shut down power for several days to about 2 million people.

Gov. Gavin Newsom, a Democrat, is among those who have criticized PG&E and other utilities for the blackouts and their handling of wildfire danger.

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Gecker reported from San Francisco. Associated Press writers Janie Har and Juliet Williams in San Francisco and John Antczak and Christopher Weber in Los Angeles contributed to this report.