ROUNDUP (AP) -- Crews are battling a stubborn central Montana wildfire that threatens ranch homes, small subdivisions and vacation cabins in the Bull Mountains north of Billings.

The Dunn Mountain fire has repeatedly jumped fire lines intended to halt its advance.

The Musselshell County sheriff's office has warned people living along Fattig Creek Road to be prepared for possible evacuation, fire information officer Jennifer Costich said Saturday.

As of early Saturday evening, fire crews were successful in keeping the flames east of Fattig Road and protecting the threatened homes, Costich told The Associated Press.

''They have numerous engine crews working those lines, trying to put out hot spots, trying to keep a handle on it,'' she said in a telephone interview. ''They've had to do some additional burnouts today around some homes ... and we have not had the severe winds today that we had feared.''

Thus far the only structure lost to the Dunn Mountain fire is a wooden railroad bridge that burned Thursday. One cow died in the fire.

The 126-square-mile fire was active all night Friday and into Saturday and crews were out all night, Costich said.

In all, 282 people are assigned to the fire along with five helicopters, 39 fire engines, 10 water tenders, six graders and five bulldozers, Costich said.