Firefighters say it make take a week to fully contain another burning in the Mark Twain National Forest.
The U.S. Forest Service believes the 400-acre fire was caused by lightning. It's burning near the small town of about 95 miles southeast of Springfield.
The forest's fire manager, Jody Eberly, says the hot, dry weather combined with steep terrain is making the work difficult. The area contains large amounts of wood and other debris left over from a 2010 tornado.
Most of the blaze is contained to National Forest land, but officials say some private lands may be affected. It is not affecting canoeing on the North Fork River.
Late last month, a 550-acre blaze within the forest, as well as several smaller fires.