LOS ANGELES — About 2,000 people were ordered to evacuate in a rural part of Northern California's scenic wine region on Thursday as a fast-moving, wind-whipped wildfire grew to about 10,000 acres in just a few hours, authorities said.
It wasn't immediately known what caused the Kincade Fire in Sonoma County north of San Francisco, said the California Department of Forestry and Fire Protection, or Cal Fire. But in a regulatory filing with the state Public Utilities Commission, California's largest utility, Pacific Gas & Electric Corp., or PG&E, said it learned that a nearby transmission tower malfunctioned about seven minutes before the fire erupted on Wednesday night.
PG&E on Wednesday began shutting off power to almost a half-million people in an attempt to avoid wildfire disasters as humidity levels have dipped and winds have gusted up to 70 mph across the region.
Authorities ordered evacuations around the rural town of Geyserville and areas east of the community, including a casino, as the fire moved westward on Thursday.
No injuries had been reported. Authorities said at least two structures had been damaged, stressing that they couldn't confirm local news reports that as many as a dozen homes had been destroyed.
Authorities said the vegetation fire was reported at 9:27 p.m. Wednesday. In its state filing, PG&E said it learned of the tower failure at 9:20 p.m. A PG&E worker who went to inspect the scene at 7:30 on Thursday morning found that state fire personnel had taped off the transmission tower and was informed about a broken jumper on the tower, the company said.
A jumper is a short wire that sends power to parts of a transmission tower.
NBC Bay Area reported that records showed that PG&E didn't cut power to the area until 23 minutes after the fire was reported and that it was seven hours more before it shut down power to nearby communities.
At a news conference late Thursday afternoon, PG&E's chief executive, Bill Johnson, said those transmission lines remained active because the company's weather forecasts, particularly wind speeds, didn't call for it.
"We relied on the protocol and still at this point do not know exactly what happened," Johnson said. He said he didn't know why it took PG&E 10 hours to send a worker out to look at the tower.
The company began shutting off power to almost a half-million people in 15 northern counties on Wednesday to protect against wildfires as hot, dry winds whipped in from offshore.
The rolling blackouts ran from the Sierra Foothills in the northeastern part of the region to parts of the more heavily populated San Francisco Bay Area. The utility said more shutoffs could be in store over the weekend when the region is hit again by dangerously windy weather.
It's the second massive blackout by the utility over fire risk in two weeks. In the first shutoff, power was cut to about 2 million people across northern and central California. In recent years, authorities have blamed electrical equipment for causing several deadly and destructive fires.
"We understand the hardship caused by these shutoffs," PG&E Chief Executive Bill Johnson said Wednesday. "But we also understand the heartbreak and devastation caused by catastrophic wildfires."
In the southern part of the state, Southern California Edison began fire-safety blackouts for more than 65,000 people on Thursday, about a third of them in Los Angeles County, where the Tick Fire erupted on Thursday afternoon and grew to 3,700 acres by 5 p.m.
The fire, near Agua Dulce in northern Los Angeles County, was racing toward residential communities in Santa Clarita, about 15 miles southwest, authorities said.
Thousands of people also lost power in heavily populated San Bernardino County, where the Old Water Fire broke out in San Bernardino National Forest overnight. About 80 homes in north San Bernardino were under evacuation orders as the fire grew to about 105 acres on Thursday afternoon, authorities said.
The blackouts didn't affect the city of Los Angeles, which is served by a different power company.
Alex Johnson and Phil Helsel reported from Los Angeles. Daniel Arkin reported from New York.