(KTLA) – A fire tornado developed as firefighters battled a fast-moving brush fire in the hilly, open terrain of northwestern Los Angeles County Wednesday.

The “Sam Fire” had burned approximately 150 acres in Gorman, near Old Ridge Route and Lancaster Road.

KTLA’s helicopter captured dramatic footage of an impressive fire tornado that developed during the brush fire battle.

Fire tornadoes, sometimes called “fire devils,” “firenadoes” or “pyrogenetic tornadoes,” occur when extreme, rising heat is met with turbulent wind conditions. The vortex of the tornado sucks in combustible gases and burning debris.

The fire department’s Air Operations Division said several “fire whirls” were spotted in the grass fire. The whirls “tell the story of dry, receptive fuels and erratic winds from intense surface heating,” the division said.

Fire whirls can be as small as 1 foot wide or as large as 500 feet wide, according to the U.S. Forest Service. “Large fire whirls have the intensity of a small tornado,” the Service says.

The Sam Fire held at about 150 acres, the fire department said. No structures were damaged and no one was injured.

It was 60% contained Wednesday night and all hot spots had been put out. Fire crews remained on the scene throughout the night.