A fast-moving wildfire ignited late Wednesday in a remote, mountainous stretch of northeastern Sonoma County, rapidly growing to 10,000 acres amid intense winds and prompting evacuations in and around Geyserville.

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The fire continued burning into Thursday morning near The Geysers geothermal plant in the Mayacamas Mountains and the glow of flames was visible throughout the area. Winds were so powerful, a gust of 76 mph was recorded near the scene of the fire, according to the National Weather Service.

Dubbed the Kincade Fire, the blaze was 0% contained as of 6:26 a.m., according to the California Department of Forestry and Fire Protection.

The fire started around 9:25 p.m. on John Kincade Road, near where Pacific Gas and Electric Co. shut off power on Wednesday afternoon — due to high fire danger — in an effort to prevent fires from being sparked by downed or damaged power lines.

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But dispatchers alerted firefighters heading to the scene that there were “possible power lines down in the area,” according to firefighter radio recordings reviewed by The Chronicle. It wasn’t immediately clear if the downed power lines were connected to the blaze, or if they were energized at the time the fire began.

As firefighters realized they would need to start evacuating residents, one firefighter alerted dispatch the power was out in the area of the 10000 block of Pine Flat Road and there was “a limited ability to make phone calls. We need to go door to door.”

Mandatory evacuations were ordered for Geyserville shortly after 6 a.m. Thursday. Prior to that, authorities issued evacuation orders for all of Red Winery Road, all of Alexander Mountain Road, Highway 128 from Geysers Road to River Road including River Rock Casino and all roads off River Road in that area, according to the Sonoma County Sheriff’s Office.

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Evacuation centers were in place at Windsor High School, 8695 Windsor Road in Windsor, and at the Healdsburg Community Center at1557 Healdsburg Avenue, according to county government officials.

Officials repeatedly urged the public to take evacuation orders seriously.

Nancy Aguirre, 16, hobbled into the Windsor High School evacuation center wearing a heavy cast on her left leg after breaking her ankle in a skateboarding accident last weekend. She said she fled her home on Chalk Hill Road, south of Healdsburg, with her mother and brother.

“The flames were like very, very close, only a couple of miles away, and there were really, really strong winds,” Aguirre said, adding that her father stayed back to help neighbors get their horses out of barns and load them up into trailers. “The horses were really freaking out and, at the same time, my parents were kind of worried about me. I was stressing out.”

She only had time to grab her school stuff, her three fish and two of the three cats.

“We could not find one of the cats,” Aguirre said. “We’re hoping the other one makes it.”

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Karen Vaughan, 56, an Oklahoma native who owns a small travel company and moved to Healdsburg six months ago, said she saw a wall of flames and freaked out, but nobody else in her neighborhood seemed to be bothered.

“I was sitting on my balcony and I looked out and I saw the whole mountainside on fire,” Vaughan said. “It looked like it was coming toward me.”

She rushed to a neighbor’s house, woke her up and tried to get her to leave.

“I said, ‘there’s a big wall of fire,’ and she said, ‘No, I’m staying.’”

Vaughan sent WhatsApp messages to all of her friends in the area and nobody responded, so she hopped into her car and drove to the Windsor High School evacuation center.

“I think people are numb and they’re used to it. It’s scary is all I can say and I’m not a fearful person,” she said. “It looked close, and these fires move quickly.”

Heavy winds and warm temperatures spurred the fire through the night. By 5 a.m., temperatures at the Santa Rosa Airport had reached 77 degrees with 11% humidity, according to the National Weather Service. Strong winds continued to gust at up to 45 mph in Sonoma County, with calmer conditions expected starting around 10 a.m.

The conditions were nearly the same as when the Tubbs Fire tore through Napa and Sonoma counties two years ago, said meteorologist Ryan Walbrun.

“Pretty much everything lined up: strong winds, dry fuels, hot temperatures and low humidity,” he said. “This is what can happen.”

State Sen. Mike McGuire, D-Healdsburg, said there aren’t many heavily populated communities near the fire, but hundreds of homes and hunting cabins are scattered throughout that part of the county.

The Sonoma County Fairgrounds opened its horse paddocks to large animal evacuations around midnight, and by 4 a.m. they were housing 29 horses and a mule, CEO Becky Bartling said.

Cierra Warner, of Santa Rosa, brought her quarter horse, Levi, and three other horses from Chalk Hill Ranch near Healdsburg. She got a Nixle alert about the fire and didn’t think much of it until her mother called her from vacation in Fiji. Warner decided to be safe and pick up her horse.

“I thought, ‘I better get out there before it gets crazy,’” Warner said. “You could definitely see it. As I was driving up there you thought you were go right through it.”

The blaze broke out after the National Weather Service issued a red flag warning for high fire danger. PG&E, whose power lines sparked many fires in the county two years ago, proactively turned off power to 178,000 customer accounts earlier in the day in 15 counties, including Sonoma.

PG&E spokeswoman Karly Hernandez said the Kincade Fire is burning “near the (shut-off) footprint and we are working to gather additional information.” The utility cut power to about 27,830 Sonoma County customers at 3 p.m., she noted.

Authorities’ biggest concern is the high wind speeds that could continue to make firefighting difficult.

An evacuation warning is in place for northern Healdsburg, the Sheriff’s Office said. But a valley floor filled with vineyards — and the Russian River — lie between the fire and those communities.

Several agencies were responding to the fire, including two strike teams each with five engines sent by the Sonoma County Fire Department.

Paul Lowenthal, Santa Rosa’s assistant fire marshal, said firefighters in the city and throughout Sonoma County “knew there was the possibility of this.”

“We had extra firefighters on duty because of the red flag warning, and we had additional police officers on duty for the (PG&E shut-offs),” he said.

During the October 2017 Tubbs Fire — California’s second-most destructive wildfire to date — Santa Rosa learned it was important to staff additional resources in advance Lowenthal said. He explained that “once an incident like this is dispatched or reported, we push all of those additional resources that were staffed up in the direction of the fire, toward the critical needs.”

The Marin County Fire Department has also sent its incident management team, Chief Jason Weber said.

David Huebel, 40, works as a vineyard manager at Hafner Vineyard, which is seven miles outside of Healdsburg. The property was hit by PG&E’s power shut-off Wednesday afternoon, and Huebel was unsure how the family-run vineyard would finish harvesting their cabernet sauvignon.

But then, around 9:35 p.m., a bigger problem loomed. Huebel had stepped outside to turn off his generator when he looked toward the Mayacamas Mountains. His father had worked there since 1984, and they always drew his attention. He saw a faint glow.

“I was asking myself, ‘Is that fire?’” Huebel said. “Everything about the scene was wrong. There shouldn’t have been light right there, it shouldn’t have been orange. It was a couple minutes later I saw a column of smoke. We watched it grow for more than two hours before we left.”

Huebel had watched the Tubbs Fire burn across Sonoma County in 2017, from Calistoga to Santa Rosa. The strange light that flickered in the hills never seemed to end. He quickly called his neighbors, alerting them to the Kincade Fire.

And when the evacuation order for Red Winery Road came at 12:32 a.m., Huebel didn’t hesitate. He left with his wife and two children, 11 and 18.

“Here we go,” he remembers thinking, “this one is too close.”

San Francisco Chronicle staff writer Lizzie Johnson contributed to this report.

J.D. Morris, Matthias Gafni, Peter Fimrite and Lauren Hernández are San Francisco Chronicle staff writers. Email: jd.morris@sfchronicle.com; matthias.gafni@sfchronicle.com; pfimrite@sfchronicle.com; lauren.hernandez@sfchronicle.com