SANTA ROSA, Calif. — Authorities in Northern California ordered 180,000 residents to flee their homes Sunday as historic winds fueled a wildfire in the wine country and led the state’s biggest utility to shut off power for millions of people in an effort to prevent more fires.
The fear that the winds could blow embers and spread fire across a major highway prompted authorities to expand evacuation orders that covered parts of Santa Rosa, a city of 175,000 that was devastated by a wildfire two years ago. The latest evacuation orders came after Pacific Gas & Electric shut off power to 2.3 million people across 36 counties starting Saturday evening.
‘‘This is the largest evacuation that any of us . . . can remember,’’ the Sonoma County Sheriff’s Office tweeted Sunday morning. ‘‘Take care of each other.’’
Later Sunday, Governor Gavin Newsom declared a statewide emergency.
Hundreds of people arrived at the Sonoma County Fairgrounds in Santa Rosa throughout the night and into Sunday morning. Some came from senior care facilities. More than 300 people slept inside an auditorium filled with cots and wheeled beds. Scores of others stayed in a separate building with their pets.
Among them was Maribel Cruz, 19, who packed up her dog, four cats and fish as soon as she was told to flee from her trailer in the town of Windsor, which is about 60 miles north of San Francisco. She also grabbed a neighbor’s cat.
‘‘I'm just nervous since I grew up in Windsor,’’ she said. ‘‘I'm hoping the wind cooperates.’’
About 90,000 residents were already under a mandatory evacuation order Saturday night that encompassed a huge swath of wine country stretching from the inland community of Healdsburg west through the Russian River Valley and to Bodega Bay on the coast, Sonoma County Sheriff Mark Essick said.
The sheriff pleaded with residents in the evacuation zone to get out immediately, citing the 24 lives lost when fire swept through the region in October 2017. He thanked residents for heeding his call and praised the smooth exodus.
‘‘Although I've heard people express concerns that we are evacuating too many people, I think those concerns are not valid at this point,’’ Essick said, noting that the winds pushed fire toward the towns of Healdsburg and Windsor overnight.
The Healdsburg area lost one of its historic attractions to the flames Sunday when embers carried by the winds sparked a blaze that engulfed the Soda Rock Winery whose buildings included a general store and post office founded in 1869. The winery was about 10 miles (16 kilometers) outside the town of Healdsburg.
The Kincade Fire began Wednesday night and is only 10% contained, the California Department of Forestry and Fire Protection said Sunday. It grew by almost 4,000 acres overnight to 30,000 acres and has destroyed 79 structures.
Fire officials said about 30,000 firefighters took an aggressive stance overnight to keep the fire from spreading.
The fire was expected to be especially unwieldly Sunday due to powerful winds gusting at up to 80 miles per hour on hillsides. The wind event was expected to last until Monday, the National Weather Service said.
Fire officials said the winds could potentially spark spot fires up to a mile away and quickly explode. They feared that if it crosses US Route 101, the fire could spread westward to an area that hasn’t had a fire in 80 years.
‘‘The fuel in that area is extremely dense, they’re extremely old and dry,’’ said Steve Volmer, a fire behavior analyst with CalFire.
Meanwhile, another blaze erupted Sunday on both sides of a San Francisco Bay Area freeway and quickly spread, coming dangerously close to homes in Vallejo, which is 55 miles south of Geyserville where the massive Kincade Fire is burning.
A live broadcast on KGO-TV showed the fire on both sides of Interstate 80 near Vallejo and homeowners using hoses on a hillside to try and fight it. Smoke from the wildfire forced a freeway to close and the evacuation of California State University Maritime Academy.
Evacuations also hit inmates at the North County Detention Facility in Santa Rosa and about 100 Sutter Santa Rosa Regional Hospital patients.
To the south, a wildfire dubbed the Tick Fire destroyed 18 structures Thursday in the Santa Clarita area north of Los Angeles. Nearly all the 50,000 residents ordered to evacuate were allowed back home after Santa Ana winds began to ease.
Marcos Briano found destroyed homes on his street.
‘‘I'm thankful that nothing happened to my house, but I feel bad for my neighbors,’’ Briano, 71, said Saturday.
As of Sunday, the Tick Fire was 65 percent contained.
What sparked the current fires is unknown, but PG&E said a 230,000-volt transmission line near Geyserville malfunctioned minutes before that blaze erupted Wednesday night.
The utility acknowledged a tower malfunction prompted a strategy change for determining when to kill high-voltage transmission lines, Andrew Vesey, CEO of Pacific Gas & Electric Co., said Friday.
The possible link between the wine country fire and a PG&E transmission line contained grim parallels to last year when most of the town of Paradise burned, killing 85 people in the deadliest US blaze in a century.
State officials concluded a PG&E transmission line sparked that fire.
PG&E said this weekend’s shut-off was affecting about 940,000 homes and businesses. The city of San Francisco was not in line for a blackout amid shut-offs for most of the rest of the San Francisco Bay Area, the wine country to the north and the Sierra foothills.
Many residents facing blackouts had barely recovered from a previous shut-off.
Northeast of Sacramento, Scott Paris estimates about $20,000 lost in shutting down his High-Hand Nursery and Cafe when PG&E cut the power earlier this month for about 24 hours during a weekday. A beautiful fall Sunday might bring $50,000 to $60,000 worth of business.
‘‘If this is the new normal, it’s going to drive up a lot of costs,’’ he said.