Smoke and heat generated by a huge wildfire in southeastern Oregon are creating massive “fire clouds” over the blaze.

The “fire clouds” are “dangerous columns of smoke and ash that can reach up to 6 miles (10 kilometers) in the sky and are visible from more than 100 miles (160 kilometers) away,” the Associated Press (AP) reported Friday.

Authorities have placed the clouds at the top of the list of the intense fire behavior they are witnessing regarding the Bootleg Fire, the biggest wildfire burning in the United States.

“The inferno grew Friday to about 75 square miles (194 square kilometers) larger than the size of New York City and was raging through a part of the U.S. West that is enduring a historic drought,” according to the AP.

Pyrocumulus clouds, also known as “fire clouds,” resemble giant, dirty-colored thunderheads sitting on top of a column of smoke coming from a wildfire.

Officials believe the Bootleg Fire may not be fully contained until the end of November, KOIN reported Friday.

“We had several days in a row of extreme fire behavior,” Marcus Kauffman, Oregon Department of Forestry spokesperson for the Bootleg Fire, told the outlet.

“Every day the fire punches up a column — the concentration of smoke — and we get the pyrocumulus cloud which is an indicator that there is so much energy coming out of the fire that it’s creating its own weather,” he said.

As of Friday evening, the fire was reportedly 22 percent contained and approximately 2,000 personnel were helping with the firefighting efforts, including resources brought in from 25 additional states, the KOIN report stated, adding the cause of the blaze remained unknown.

In a social media post on Friday night, the National Weather Service Boise said the Bootleg Fire “is now producing lightning within its explosive pyrocumulus cloud”:

“As this fire creates its own weather, the volatile nature makes it extremely dangerous for firefighters. Smoke continues to pour into E Oregon & Idaho,” the agency concluded.