The Buzzard complex is burning 45 miles northeast of Burns, in southwest Oregon. While the fire moved south and east Monday, jumping a state highway, firefighters, working into the small hours Tuesday, were able to keep it away from homes.
Fire crews focused Tuesday on setting up lines around the blaze to keep it from spreading, Tara Martinak, a spokeswoman for the state Bureau of Land Management, told the Oregonian.
To the west, the Moccasin Hill fire near Klamath Falls was reported to be 15 percent contained. The fire has burned 20 buildings, including six houses.
The fire was first reported Sunday, when thousands of lightning strikes caused dozens of wildfires.
The Jack Knife fire near the John Day River and Grass Valley had spread over 3,500 acres. The Shaniko Butte fire near Warm Springs was only at 300 acres but threatened some homes.
California, Oregon and Washington have been having an unusually active fire season for early summer because of a prolonged drought. Normally, the region's cool wet winters protect grasslands and woods until they are dried out in the summer.