CRAIG — A wildfire in northwestern Colorado has quadrupled to more than 31 square miles, or about 20,000 acres.

Fire managers said Thursday the Alkali Fire has destroyed a cabin, barn and propane tank.

No injuries have been reported.

Three head of cattle have been killed and ranchers have moved other livestock.

Spokeswoman Lynn Barclay of the Northwest Colorado Fire Management Unit says pipelines, a transfer station and other oil and gas facilities are threatened. It wasn't immediately clear how serious the threat was.

The fire is on federal and private land about 14 miles north of Craig and 150 miles northwest of Denver. The cause hasn't been announced.

About 70 firefighters are on the scene. Barclay says they face temperatures around 90 degrees, erratic winds and possible thunderstorms.