GRIZZLY FLATS, Calif. (AP) — A wildfire raged through a small Northern California forest town Tuesday, burning dozens of homes as dangerously dry and windy weather also continued to fuel other massive blazes and prompted the nation's largest utility to begin shutting off power to 51,000 customers.

The Caldor fire in the northern Sierra Nevada had burned an estimated 50 homes in and around Grizzly Flats, a town of about 1,200 people, fire officials said at a community meeting.

Gov. Gavin Newsom proclaimed a state of emergency for El Dorado County because of the blaze, which tripled in size between Monday and Tuesday afternoon to nearly 50 square miles (129 square kilometers),

To the north the Dixie Fire — the largest of some 100 active wildfires in more than a dozen Western states — was advancing toward Susanville, population about 18,000.

Meanwhile, Pacific Gas & Electric announced it had begun shutting off power to some 51,000 customers in small portions of 18 northern counties to prevent winds from knocking down or fouling power lines and sparking new blazes.

The utility said the precautionary shutoffs were focused in the Sierra Nevada foothills, the North Coast, the North Valley and the North Bay mountains and could last into Wednesday afternoon.

Very few homes were left standing in Grizzly Flats, where streets were littered with downed power lines and poles. Houses were reduced to smoldering ash and twisted metal with only chimneys rising above the ruins. A post office and elementary school were also destroyed.

Two people with serious or severe injuries were airlifted to hospitals from the Grizzly Flats area, fire officials said.

Derek Shaves and Tracy Jackson were helping their friend salvage food and other supplies from the Grizzly Pub & Grub, a business in the evacuation zone that wasn't touched by the blaze.

Shaves said he visited Grizzly Flats Tuesday and saw his home and most of the houses in his neighborhood had been destroyed by the fire.

“It’s a pile of ash,” he said. “Everybody on my block is a pile of ash and every block that I visited — but for five separate homes that were safe — was totally devastated.”

At the Dixie Fire, numerous resources were put into the Susanville area, where residents were warned to be ready to evacuate, said Mark Brunton, an operations section chief.

“It's not out of play, and the next 24 hours are going to be crucial to watch as to what the fire is going to do there,” he told an online briefing.

To the east, spot fires became established south of the small community of Janesville, which had been ordered evacuated. Some structures were lost there — images captured by The Associated Press showed a home consumed by flames — but a surge of firefighters was able to herd the fire around the majority of the town, Brunton said.

The Dixie Fire, which had burned some 600 homes, is the largest of the major wildfires burning in Western U.S. states that have seen historic drought and weeks of high temperatures and dry weather that have left trees, brush and grasslands as flammable as tinder. Climate change has made the U.S. West warmer and drier in the past 30 years and will continue to make the weather more extreme and wildfires more destructive, according to scientists.

Susanville is the seat of Lassen County and the largest city that the Dixie Fire, named for the road where it started, has approached since it broke out last month. The former Sierra Nevada logging and mining town has two state prisons, a nearby federal lockup and a casino.

Ash fell from the advancing fire, and a police statement urged residents “to be alert and be ready to evacuate” if the fire threatens the city.

The Dixie Fire has scorched more than 940 square miles (2,434 square kilometers) in the northern Sierra Nevada and southern Cascades since it ignited on July 13 and eventually merged with a smaller blaze. It’s less than a third contained.

Investigations are continuing, but PG&E has notified utility regulators that the Dixie and Fly fires may have been caused by trees falling into its power lines. The Dixie Fire began near the town of Paradise, which was devastated by a 2018 wildfire ignited by PG&E equipment during strong winds. Eighty-five people died.

Ongoing damage surveys have counted more than 1,100 buildings destroyed, including 630 homes, and more than 16,000 structures remained threatened. Numerous evacuation orders were in effect.

Near the Caldor Fire, people were offering assistance to evacuees, including the four-footed kind. Susan Collins of Placerville used her horse trailer to help move two horses Tuesday after offering help on an El Dorado County Facebook page.

“I know not everybody is prepared when something like this happens, and my purpose in life is to be there to help people,” she said.

Across the state line in Nevada, school administrators delayed start times in the Reno-Sparks because of a cloak of wildfire smoke from the Dixie Fire blanketing the region. Smoke plumes from the Caldor Fire were also visible from northern Nevada.

Two dozen fires were burning in Montana and nearly 50 more in Idaho, Washington and Oregon, according to the National Fire Interagency Center.

In Montana, authorities ordered evacuations on Tuesday for several remote communities in north- central Montana as strong winds propelled a large wildfire toward inhabited areas.

The mandatory evacuation covered Lodge Pole, a town of about 300 people on the Fort Belknap Indian Reservation, and the former mining town of Zortman, which has about two dozen people, KOJM reported.

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John Antczak reported from Los Angeles. Associated Press writers Olga R. Rodriguez in San Francisco, Amy Taxin in Orange County, Samuel Metz in Carson City, Nevada, and Matthew Brown in Billings, Montana, contributed to this report.