MAYBELL, Colo. (AP) — A lightning-caused wildfire in northwestern Colorado is threatening some structures as erratic winds push the flames in multiple directions.

Fire managers said Monday the Pine Tree Fire has burned about 4,000 acres in grassland, sagebrush and small trees. It started Saturday.

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Pine Tree Fire (credit: Moffat County)

The fire is about 15 miles south of the town of Maybell and 200 miles northwest of Denver.

Pine Tree Fire (credit: Moffat County)

Officials didn’t say how many structures are threatened. Firefighters said they did not yet have any containment lines around the blaze.

It is believed to have been started by lightning.

Pine Tree Fire (credit: Moffat County)

The Deep Creek Fire was was burning in trees and brush about 50 miles (80 kilometers) east of the Pine Tree Fire.

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Pine Tree Fire (credit: Moffat County)

It was about 62 percent contained Monday at 4,100 acres.

It started Sept. 4. The cause had not been determined.

Wildfire Resources

– Visit CBSDenver.com’s Living With Wildfire section.

Wildfire Photo Galleries

– See images from the most destructive wildfires (Black Forest, Waldo Canyon, High Park and Fourmile) and largest wildfire (Hayman) in Colorado history.

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