GREENVILLE, Calif. (AP) — A 3-week-old wildfire engulfed a tiny Northern California mountain town, leveling most of its historic downtown and leaving blocks of homes in ashes, while a new wind-whipped blaze destroyed homes as crews braced for another explosive run of flames Thursday amid dangerous weather.

The Dixie Fire, swollen by bone-dry vegetation and 40 mph (64 kph) gusts, raged through the northern Sierra Nevada community of Greenville on Wednesday evening. A gas station, church, hotel, museum and bar were among fixtures gutted in the town dating to California’s Gold Rush era that had some wooden buildings more than 100 years old.

The fire “burnt down our entire downtown. Our historical buildings, families homes, small businesses, and our children’s schools are completely lost,” Plumas County Supervisor Kevin Goss wrote on Facebook.

“We lost Greenville tonight,” U.S. Rep. Doug LaMalfa, who represents the area, said in an emotional Facebook video. “There’s just no words.”

As the fire’s north and eastern sides exploded Wednesday, the Plumas County Sheriff’s Office issued an urgent warning online to the town’s approximately 800 residents: “You are in imminent danger and you MUST leave now!”

A similar warning was issued Thursday for residents of another tiny mountain community, Taylorsville, as flames pushed toward the southeast.

To the northwest, crews were protecting homes in the town of Chester. Residents there were among thousands under evacuation orders or warnings in several counties, but no injuries or deaths were immediately reported.

Margaret Elysia Garcia, an artist and writer who has been in Southern California waiting out the fire, watched video of her downtown Greenville office in flames. The office contained every journal she’s written in since second grade and a hand edit of a novel on top of her grandfather’s roll-top desk.

“We’re in shock. It’s not that we didn’t think this could happen to us,” she said. “At the same time, it took our whole town.”

Firefighters on Wednesday had to deal with people reluctant to leave. Their refusals meant that firefighters spent precious time loading people into cars to ferry them out, said Jake Cagle, an incident management operations section chief.

“We have firefighters that are getting guns pulled out on them, because people don’t want to evacuate,” he said.

The blaze that broke out July 21 is the largest burning in California and had blackened over 504 square miles (1,305 square kilometers), an area larger than Los Angeles. The cause was under investigation but Pacific Gas & Electric has said it may have been sparked when a tree fell on one of its power lines.

The fire was near the town of Paradise, which largely was destroyed in a 2018 wildfire that became the nation’s deadliest in at least a century and was blamed on PG&E equipment.

Ken Donnell left Greenville on Wednesday, thinking he’d be right back after a quick errand a few towns over, but couldn’t return as the flames swept through. All he has now are the clothes on his back and his old pickup truck, he said. He’s pretty sure his office and house, with a bag he had prepared for evacuation, is gone.

Donnell remembered helping victims of 2018’s devastating Camp Fire, in which about 100 friends lost their homes.

“Now I have a thousand friends lose their home in a day,” he said.

By Thursday, the Dixie Fire had become the sixth largest in state history, the California Department of Forestry and Fire Protection said. Four of the state’s other five largest fires happened in 2020.

The fire forced Lassen Volcanic National Park to close to visitors.

Dozens of homes had already burned before the flames made a new run Wednesday. The U.S. Forest Service said initial reports show that firefighters saved about a quarter of the structures in Greenville.

“We did everything we could,” fire spokesman Mitch Matlow said. “Sometimes it’s just not enough.”

About 100 miles (160 kilometers) south, officials said between 35 and 40 homes and other buildings burned in the fast-moving River Fire that broke out Wednesday near Colfax, a town of about 2,000. Within hours, it ripped through nearly 4 square miles (10 square kilometers) of dry brush and trees. There was no containment and about 6,000 people were ordered to evacuate in Placer and Nevada counties, Cal Fire said.

In Colfax, Jamie Brown ate breakfast at a downtown restaurant Thursday while waiting to learn if his house was still standing.

He evacuated his property near Rollins Lake a day earlier, when “it looked like the whole town was going to burn down.” Conditions had calmed a bit by Thursday, and he was hoping for the best.

“I figure I better have a nice breakfast before I lose my home,” he said.

After firefighters made progress earlier this week, high heat, low humidity and gusty winds erupted Wednesday and were expected to be a continued threat.

Winds were expected to change direction multiple times Thursday, putting pressure on firefighters at sections of the fire that haven’t seen activity in several days, officials said.

The trees, grass and brush were so dry that “if an ember lands, you’re virtually guaranteed to start a new fire,” Matlow said.

Heat waves and historic drought tied to climate change have made wildfires harder to fight in the American West. Scientists say climate change has made the region much warmer and drier in the past 30 years and will continue to make weather more extreme and wildfires more frequent and destructive.

About 150 miles (240 kilometers) west of the Dixie Fire, the lightning-sparked McFarland Fire threatened remote homes along the Trinity River in the Shasta-Trinity National Forest. There was little containment of the fire after it burned nearly 33 square miles (85 square kilometers) of drought-stricken vegetation.

Risky weather also was expected across Southern California, where heat advisories and warnings were issued for inland valleys, mountains and deserts for much of the week.

More than 20,000 firefighters and support personnel were battling 97 wildfires covering 2,919 square miles (7,560 square kilometers) in 13 U.S. states, the National Interagency Fire Center said.

Early in the week, some 5,000 firefighters had made progress on the Dixie Fire, saving some threatened homes, bulldozing pockets of unburned vegetation and managing to surround a third of the perimeter.