A fast-moving wildfire, spurred by powerful winds, burned through Northern California on Thursday and forced thousands of people to evacuate parts of Sonoma County — the rural wine country 75 miles north of San Francisco that is still recovering from a deadly 2017 blaze.

Pacific Gas & Electric, the state’s largest utility, told state regulators on Thursday that a jumper on one of its transmission towers broke close to where officials say the Kincade Fire started, near Geyserville.

Although PG&E cut power in the area on Wednesday afternoon amid dangerous weather, stretches of the company’s high voltage power transmission lines — which were responsible for the state’s deadliest wildfire ever — were still operating in the area when the fire broke out, the utility said in a statement.

In the report it filed with the California Public Utilities Commission, PG&E said it became aware of the transmission tower malfunction at 9:20 local time Wednesday. The fire began at 9:27 p.m., according to California Department of Forestry and Fire Protection.

PG&E CEO Bill Johnson said the company is conducting an internal investigation, but said it has not accepted responsibility for the fire, adding that officials still don’t know precisely how it started.

“We still, at this point, do not know what exactly happened,” he said at a news conference.

After it sparked late Wednesday night, the fire spread rapidly. More than 16,000 acres were charred through Thursday night. At one point, it was growing at a rate of 30 football fields per minute. Authorities struggled against the strong winds on Thursday, and the fire remained almost entirely uncontained by nightfall, state authorities said. No injuries have been reported, but nearly 50 structures have been damaged or destroyed.

Meanwhile, 400 miles south, a rapidly expanding fire burned through Canyon Country, in northwest Los Angeles County, covering more than 5,000 acres by Thursday evening.

Forecasters expect conditions across California to get worse in the coming days, and PG&E warned even more blackouts will follow, a desperate hedge against further wildfire risk. The company said the next round of outages could begin Saturday and would be “on the magnitude” of those earlier this month, the most extensive planned power shutdown ever.

As the Kincade Fire spread, the Sonoma County Sheriff’s Office ordered mandatory evacuations, including for the entire community of Geyserville, and shut down several major roads.

“This is not the time to stay,” Sonoma Sheriff Mark Essick said at a news conference. “This is the time to go.”

As the wildfire torched Sonoma, and others spread in San Bernardino, Los Angeles County and elsewhere, Gov. Gavin Newsom (D) railed against all three of the state’s investor-owned power companies, including PG&E, which has already been forced into bankruptcy in the face of billions of dollars in liability claims stemming from previous fires.

“I must confess, it is infuriating beyond words,” Newsom said, accusing the utilities of neglecting their infrastructure and leaving the state vulnerable to fires sparked by outmoded power lines.

His statements echoed those he made two weeks earlier, when PG&E shut off power to nearly a million customers.

“It’s more than just climate change, and it is climate change, but it’s more than that,” Newsom said. “As it relates to PG&E, it’s about dog-eat-dog capitalism meeting climate change, it’s about corporate greed meeting climate change, it’s about decades of mismanagement.”

Newsom sent a letter Thursday to the CEOs of San Diego Gas & Electric Company, Edison International and PG&E demanding better communication about when the utilities would implement precautionary power shut-offs.

“The only consistency has been inconsistency,” he wrote.

In this case, PG&E cut off its lower-voltage distribution lines, which are more vulnerable to wind, but kept its higher-voltage transmission lines running, said Johnson, the utility’s chief.

He said the tower that broke down is 43 years old, which, he said, is “not an old tower.” Johnson said it’s been inspected four times in the last two years.

“It appeared to have been in excellent condition, recently inspected,” he said.

The state’s electric infrastructure will face more tests in the next several days. Weather forecasts in Northern and Southern California have been ominous, portending more blackouts and, perhaps, more fires. The National Weather Service said “pockets of critical fire weather” were likely.

NWS issued red flag warnings on Thursday for much of the San Francisco Bay area, including the region where the Kincade Fire is burning, as blustering offshore winds met dry air and created tinderbox conditions.

The offshore gusts, known as “El Diablo” winds, bring extremely dry air, with relative humidity plummeting to the single digits in some cases, making fire fighting particularly difficult. Forecasters expect a second round of those winds to blow across much of California in the coming days.

Meanwhile, in Southern California, “extremely critical” fire risk was predicted, with strong offshore winds, known there as Santa Ana winds, gusting up to 65 mph in parts of Ventura and Los Angeles counties through Friday.

“The fuels and vegetation are critically dry. The expected weather will create an environment ripe for large and dangerous fire growth, especially Thursday and Friday,” the NWS forecast office in Los Angeles wrote.

True to the forecast, the Tick Fire sprung up in Los Angeles County Thursday afternoon and continued to grow quickly — and totally uncontained — into the evening. Video from local media showed fire bearing down on a Canyon Country neighborhood, the flames moving steadily toward homes as residents fled.

Thursday’s raging fires, along with the Saddleridge blaze earlier this month and the Tenaja Fire in September, signal the onset of yet another dangerous wildfire season in California, where conflagrations of historic proportions have become commonplace.

Last year, the Camp Fire devastated Paradise and killed 85 people and the Woolsey Fire ravaged 100,000 acres north of Los Angeles and killed three. In 2017, the Tubbs fire ripped through Santa Rosa — near where Kincade burns now — and killed 22 people.

By now, Californians have grown accustomed to the telltale signs of a fire in progress: the glowing red hills, the skies grayed out with smoke and ash and the dire air quality warnings.

“This is the new normal that we live in,” David Hagele, mayor of Healdsburg, just south of Geyserville, told the San Francisco Chronicle. “It’s disheartening, and it’s scary for a lot of people because it does bring back a lot of scary memories from a couple of years ago.”

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