Officials ordered evacuations for campgrounds and approximately 150 structures and residences on the east side of Casper Mountain on Sunday after a fire grew rapidly on the southeast side of the mountain.
Approximately 400 residents were evacuated, according to the Wyoming State Forestry Incident Information System.
The fire has reached at least several hundred acres, said Natrona County Emergency Management Coordinator Stewart Anderson. It is not contained.
The fire is threatening areas east of South Circle Drive from the Sheep Wagon Hill area, south of the East End.
Witness Randy Evans said he first saw the flames coming from the west, south of Casper Mountain Road, just past Beartrap Meadow.
Donna Swingholm was working to evacuate her approximately 20 dogs, horses, llamas, cats and donkeys from her ranch on the south side of Casper Mountain, on Casper Mountain Road.
Swingholm was alerted by her neighbors.
"They came flying down here in their pick-up," she said. Swingholm said once she spotted the flames, "I've never seen anything move so fast in my life."
The fire was close enough to her home to steam off the side, she said.
The Natrona County Sheriff's Office confirmed the fire burned at least one structure. Officials didn't have an estimate on the size of the blaze.
Smoke from the fire was visible from Casper shortly after it was reported about 4 p.m.
Casper Mountain Road was closed for some of Sunday evening but officials opened it about 8 p.m. It will continue to be closed at Bear Trap. East End road is closed.
The evacuations included nearby campgrounds and Casper Mountain Trails Center. Residents on the east side of the mountain were encouraged to evacuate as well.
Flames were also visible from Interstate 25 east of Casper and on the south end of Casper Mountain Road.
Local officials, including the mountain's volunteer fire department, were responding to the fire. Planes and helicopters, dumping fire retardant, were also assisting.
Officials did not know what started the fire.
The American Red Cross has set up a center at the Parkway Plaza for those evacuated Sunday evening. The organization has partnered up with The Salvation Army to feed everyone, including the firefighters, said Branch Director Traci Aguilar.
"Depending on how everything pans out tomorrow, we will set up a shelter," she said.
If citizens would like to make a cash donation to the Red Cross, they can stop by the office at 318 W. B St., Casper, 82601. The Red Cross does not accept clothing, but cash donations allow them to purchase food, hotel rooms, blankets and cots. Anyone who wants to volunteer hours can call 307-237-8436 for more information.