ROUNDUP, Mont. (AP) — Officials say a wildfire south of Roundup has jumped a southern perimeter built by firefighters, forcing authorities to evacuate more homes.

The Dahl fire was last estimated at 18,500 acres Wednesday afternoon, but it was still spreading after having burned dozens of homes since it was reported on Tuesday.

Musselshell County Sheriff Woody Weitzeil tells the Billings Gazette that at least one person is unaccounted for and several animals have been lost to the fire.

To the southeast, the Ash Creek fire near the Northern Cheyenne Indian Reservation has burned 18 homes and grown to 110,000 acres as of Wednesday afternoon.

Near Helena, fire officials say the Corral fire is now 35 percent contained and some residents have been allowed back in their homes.

After two days of high temperatures and strong winds, firefighters took advantage of cooler weather to keep the blaze in check.