A fire on the Warm Springs Indian Reservation in Central Oregon has expanded into a forested upland, complicating the battle against a 6-day-old blaze.

The growth of the Sunnyside Turnoff fire has slowed -- it's now estimated at 74 square miles. But the projected date for containing it has been pushed back from Sunday to next Thursday.

The reservation fire started Saturday in grass, sagebrush and juniper. Fire information officer Bill Queen said Thursday it has spread north to the Mutton Mountains.

The area is marked by a tree common in Oregon's eastern forests, the Ponderosa pine. Wildfires in trees can expand quickly by racing up and spreading through the crowns.

Meanwhile the Kah-Nee-Ta resort on the reservation said it would reopen part of its operation Thursday.