Massive fire near Oroville forces thousands to flee

As California braced for a dangerous, prolonged heat wave that's expected to last through next week, firefighters across the state were already battling several new wildfires, some serious enough to force evacuations.

The most dangerous fire was burning in Oroville. The Thompson fire spurred an evacuation order affecting thousands in and around the city and Butte County after it broke out just before 11 a.m. Tuesday, according to Dan Collins, a fire captain at Cal Fire's Butte County station.

The fire is threatening about 230 structures in the area. Collins said PG&E de-energized the power lines in the area after the flames broke out. The fire had zero containment as of Tuesday night.

Images on social media and the local news showed several buildings burning in Oroville, but the exact number of structures burned was unclear.

Much of Northern California remained under a red flag warning — an alert for extreme fire weather — as well as an excessive heat warning . The red flag alert warned of a combination of winds up to 30 mph, low humidity and hot temperatures that “can contribute to extreme fire behavior,” according to the National Weather Service .

At least four new fires ignited in the region Tuesday, according to the California Department of Forestry and Fire Protection.

Given the conditions, Pacific Gas & Electric Co. initiated its first public safety power shutoffs of the year, affecting 2,000 customers across eight counties — Butte, Colusa, Lake, Napa, Solano, Sonoma, Tehama and Yolo. The shutoffs, which are expected to last at least through Wednesday, are meant to prevent the utility’s equipment from sparking fires during dangerous conditions.

The Thompson fire quickly grew to almost 100 acres on Tuesday, burning through mostly grassland, Collins said. By sunset, the fire had blackened 2,135 acres and spurred the city of Oroville to declare a state of emergency. Roughly 13,000 people live in the area within the evacuation perimeter, a Butte County sheriff's spokesperson said. A Cal Fire official estimated that as many as 2,000 had left their homes as of late Tuesday.

Fire crews in Butte County had one advantage: The Thompson fire was burning close to Lake Oroville, allowing water-dumping helicopters to make "quick turnarounds" between the massive reservoir and the front edge of the blaze, Cal Fire said.

In Napa County north of Calistoga, the Toll fire began just before 10 a.m. Tuesday and had grown to about 50 acres by the afternoon, according to Cal Fire.

The wind-driven fire closed at least one road in the area and prompted several evacuation orders and warnings, affecting just over 100 people in the area, according to Jason Clay, a Cal Fire spokesperson at the Sonoma-Lake-Napa station. By evening, crews had managed only 15% containment of the fire.

The conditions in the area are ripe for further wildfires to erupt, Clay said.

"The grasses are really dry," said Clay, who also noted the area's red flag warning. "That combination is all aligning, [and] that could lead to extreme fire behavior."

Fire officials have continued to warn that once vegetation fully dries out — typically by midsummer — wildfires could really ramp up, given the profusion of grass and brush that grew after two winters with heavy precipitation.

“Avoid activities that could spark a wildfire, such as parking on dry grass, dragging chains, or using equipment during the hottest parts of the day. Remember, one less spark means one less fire,” Cal Fire advised on social media.

Daniel Swain, a UCLA climate scientist, called it “essentially inevitable” that wildfires would continue to start and grow during the heat wave — which was just getting started Tuesday — given the threat of further fire starts from the holiday weekend’s fireworks and firecrackers, the hot temperatures and the buildup of dry fuels.

“It’s a pretty bad combination, honestly, to have a potentially record-breaking heat wave that starts off with dry north winds,” Swain said in a briefing Monday . “Buckle up, I think California’s fire season is likely to escalate considerably over the next five to seven days.”

In eastern San Diego County, another large fire continued to grow after sparking Monday. The McCain fire, burning just off Interstate 8, was 30% contained Tuesday night, having scorched 1,362 acres, according to Cal Fire. The fire had prompted multiple evacuation orders and warnings, affecting about 140 people, according to Mike Cornette, a fire captain with the San Diego County Cal Fire team.

Authorities closed a section of the westbound lane of Interstate 8, but the eastbound lane remained open, Cornette said. A definitive cause of the fire is still under investigation, but Cornette said it was probably caused by a traffic collision that caused a vehicle to become engulfed in flames. He said about 150 structures were threatened, but none had been damaged.

"Right now, there's not a whole lot of smoke coming off the fire, but the fire is still active," said Cornette, who expected that it would take several more days before the fire could be fully contained.

Two other small fires had also sparked Tuesday in Northern California: the Denverton fire in Solano County and the Yolla fire in Shasta County, both smaller than 30 acres as of Tuesday afternoon.

Crews were also still fighting the Basin fire , which had burned more than 13,000 acres in the Sierra National Forest in Fresno County as of Tuesday. It was 26% contained, according to Cal Fire.

That blaze is burning not far from the Balch Camp, an isolated community from which more than 150 people were evacuated because of the flames. PG&E has power infrastructure there, but a spokesperson for the utility said none of its facilities had been affected as of Tuesday morning.

Times staff writer Rachel Uranga contributed to this report.

This story originally appeared in Los Angeles Times .