The Camp 5 Fire - the Black Hills' first large wildfire of the year - broke out on Black Hills National Forest land about 1? miles northwest of Galena Sunday afternoon and quickly grew to about 100 acres.
Engines from the Black Hills National Forest, the state, several volunteer fire departments and hand crews were on the scene. An airplane joined the firefighting effort Monday.
Firefighters said the fire has been active, with flames crowning and running through the tree tops. Spot fires and flare-ups were reported 200 yards ahead of the main fire line.
Fire officials reported Sunday night that private land was threatened but that no structures were in the line of fire. A reporter on the scene said some voluntary evacuations were under way, but dispatchers said the evacuations were not at the request of authorities.
U.S. Highway 14-A _ the Boulder Canyon Highway _ was closed for about two hours and was reopened about 7:30 p.m. Sunday.
No early word is available on the cause of the fire.