This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

A massive wildfire that burned into revered Yosemite National Park was caused when a hunter “allowed an illegal fire to escape,” the U.S. Forest Service announced Thursday.

Firefighters stand at the ready as smoke rises from a managed burn along Highway 120 near the Big Oak Flat entrance to Yosemite National Park on Aug. 28. (credit: Los Angeles Times)

A local fire official had said last month that an illegal pot-growing operation was the suspected cause of the Rim Fire, which had grown to more than 370 square miles since it was ignited Aug. 17 in the Stanislaus National Forest.

On Thursday morning, the Forest Service announced that its law enforcement branch and the Tuolumne County District Attorney’s Office had determined the fire began when a hunter’s blaze escaped his or her control.

“There is no indication the hunter was involved with illegal marijuana cultivation on public lands and no marijuana cultivation sites were located near the origin of the fire,” the Forest Service news release stated. “No arrests have been made at this time and the hunter’s name is being withheld pending further investigation.”

The fire, burning in a rugged, mountainous area known as Jawbone Ridge, was 80 percent contained Thursday.

Some 4,500 structures had been threatened by the fire, and more than 100 were burned, including 11 homes, according to an official blog set up to provide information on the Rim Fire. The huge blaze — the fourth-largest in California history — had also threatened San Francisco’s water supply.

About 4,000 firefighters and other public safety workers were battling the fire. The fight had cost $81 million as of Thursday, the blog stated.

Several popular areas of iconic Yosemite National Park had been closed because of the fire, and Highway 120, which runs through the park, was partially shut down.