GREENVILLE, Calif. — California’s largest single wildfire in recorded history continued to grow Wednesday after destroying more than 1,000 buildings, nearly half of them homes, while authorities in Montana ordered evacuations as a wind-driven blaze roared toward several remote communities.

The dangerous fires were among some 100 large blazes burning across 15 states, mostly in the West, where historic drought conditions have left lands parched and ripe for ignition.

Burning through bone-dry trees, brush and grass, the Dixie Fire has destroyed at least 1,045 buildings, including 550 homes, in the northern Sierra Nevada. Newly released satellite imagery showed the scale of the destruction in the small community of Greenville that was incinerated last week during an explosive run of flames.

The Dixie Fire, named after the road where it started on July 14, by Wednesday morning covered 783 square miles and was 30% contained, according to the California Department of Forestry and Fire Protection. At least 14,000 remote homes were still threatened.

The Dixie Fire is the largest single fire in California history and the largest currently burning in the U.S. It is about half the size of the August Complex, a series of lightning-caused 2020 fires across seven counties that were fought together and that state officials consider California’s largest wildfire overall.

The fire’s cause was under investigation. Pacific Gas & Electric has said it may have been sparked when a tree fell on one of its power lines.

California authorities arrested a man last weekend who is suspected in an arson fire in remote forested areas near the Dixie Fire.

The 47-year-old suspect was charged with setting a small blaze in Lassen County, which is among the counties where the larger blaze is burning, around July 20.

In southeastern Montana, the uncontrolled Richard Spring Fire continued to advance Wednesday toward inhabited areas in and around the sparsely-populated Northern Cheyenne Indian Reservation, after several thousand people were ordered to evacuate the previous night.

Two homes caught fire Tuesday but were saved, authorities said.

The fire began Sunday and powerful gusts caused it to explode across more than 230 square miles.

A few miles from the evacuated town of Lame Deer, Krystal Two Bulls and some friends stuck around to clear brush from her yard in hopes of protecting it from the flames. Thick plumes of smoke rose from behind a tree-covered ridgeline just above the house.

“We’re packed and we’re loaded so if we have to go, we will,” Two Bull said. “I’m not fearful; I’m prepared. Here you don’t just run from fire or abandon your house.”

Some of the people who fled the fire Tuesday initially sought shelter in Lame Deer, only to be displaced again when the fire got within several miles.

The town of about 2,000 people is home to the tribal headquarters and several subdivisions and is surrounded by rugged, forested terrain. By late Wednesday a second fire was closing in on Lame Deer from the west, while the Richard Spring fire raged to the east.

Also ordered to leave were about 600 people in and around Ashland, a small town just outside the reservation with a knot of businesses along its main street and surrounded by grasslands and patchy forest.

The flames were within several miles of town and came right up to a subdivision outside it.

Local, state and federal firefighters were joined by ranchers using their own heavy equipment to carve out fire lines around houses.

Heat waves and historic drought tied to climate change have made wildfires harder to fight in the American West.

Scientists have said climate change has made the region much warmer and drier in the past 30 years and will continue to make the weather more extreme and wildfires more frequent and destructive. The fires across the West come as parts of Europe are also enduring large blazes spurred by tinder-dry conditions.