NEOLA, Utah ” A deadly wildfire in northeastern Utah grew to more than 62 square miles Tuesday, although much of the expansion occurred in the Ashley National Forest and away from small rural communities, officials said.

Since Friday, when three people were killed, the fire has burned nearly 40,000 acres, about one-third in the national forest and the rest on a mix of private and public lands and the Uintah and Ouray Indian reservations.

The fire is burning north of Neola, about 100 miles east of Salt Lake City.

Fire officials want to let the fire burn to clear out dead trees in the national forest.

Some small communities in the area still were under a mandatory evacuation.

Gov. Jon Huntsman planned to see the fire from an airplane Tuesday. He deployed 100 National Guard troops Monday to enforce road blocks and assist local police away from the flames.

Parts of the forest and several roads leading to the fire were closed to the public. It’s unclear how many buildings have burned, and the cause of the fire was still under investigation.