Winds blowing west on Sunday evening pushed a lightning-caused fire over Coal Mountain, burning an unknown acreage of grass, sagebrush and trees.

Authorities asked area residents who live along Goose Egg Road east of Casper to evacuate.

Meanwhile, Natrona County Sheriff's Deputy Cathy Potter had parked her vehicle blocking access to the road to all but firefighting crews and vehicles.

The fire lit up the sky and reflected off its smoke as lightning danced across Casper Mountain to the north of Coal Mountain.

Scores of passers-by stopped along Wyoming Highway 220 or parked across the highway from Goose Egg Road to watch, which garnered the scorn of Natrona County commissioner Cathy Killean

"I can understand people wanting some excitement, but don't be macabre," Killean said.

Killean, who lives in Bessemer Bend, gave Potter and firefighters names of area residents, including some who are elderly, she said. "I don't think there are more than 50 (residents)."

Firefighters told her that the blaze probably would not jump the highway, she said.

Mark Harshman, chief of operations at the Casper Fire-EMS, said he did not know the size of the fire, which was moving southeast along the ridge of Coal Mountain.

The only structures that might have been threatened were those along Goose Egg Road, he said before meeting with other Casper firefighters and driving up the mountain.

By Sunday afternoon, firefighters already had extinguished about 10 small fires around the county, said Dave Baker, inspector with the Natrona County Fire Protection District.

Besides the Fire Protection District and the Casper Fire-EMS, equipment and crews from the Mills Fire Department also were involved.

The fire probably began by lightning strikes between 4:30 p.m. and 4:50 p.m. on the Bates Creek Ranch including Coal Mountain across Jackson Canyon from Casper Mountain, said Sen. Charles Scott, R-Casper.

"It's entirely on our ranch," Scott said.

The fire was on very rugged terrain, some of which was burned by the Coal Mountain fire of 2000.

The 2000 fire torched 5,900 acres - almost nine square miles - of government and private land, and was fought by more than 300 firefighters from across the nation.

On Sunday, the new fire got encouragement from a rare east-to-west wind, which prevented it from heading east to Casper Mountain, Scott said.

"To me, it doesn't look like it would do any harm," he said.

If the fire were to change direction, however, it could travel through Jackson Canyon, which is full of chest-high sagebrush, he said.

Some grassy areas are dominated by the invasive, nonnative cheat grass, Scott added. "That stuff burns like kerosene."

The years of drought have so dried the vegetation that this fire burned downhill instead of uphill, he said.

"This burned downhill, which is a testament to the dry conditions," Scott said.

Reporter Tom Morton can be reached at (307) 266-0592, or at Tom.Morton@casperstartribune.net.