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By MATTHEW BROWN Associated Press

BILLINGS — A break in the weather on Thursday allowed firefighters to resume their fight against a central Montana wildfire that has charred an estimated 61,000 acres — or more than 95 square miles.

The size of the blaze is double the estimate given late Wednesday, but fire officials said it had not grown significantly overnight. They attributed the change to better mapping attained through an aerial survey of the Dunn Fire Thursday morning.

No evacuations have been ordered. Nine ranch houses were threatened and a bridge along Railroad Creek Road in Yellowstone County was destroyed.

Strong winds had caused the blaze to expand rapidly Wednesday through a mixture of grasslands, sage brush and ponderosa pine stands. That forced firefighters to suspend efforts to put it out.

But with lighter winds slowing that expansion by Thursday, crews stepped up their attack on the fire, said fire information officer Dwayne Andrews. Winds of 5 to 15 miles per hour were forecast, with gusts possible up to 40 miles per hour.

‘‘It’s full bore today,’’ said Andrews. ‘‘We’ve got 25 wildland fire engines working on hot spots.’’

The front of the east-moving blaze was roughly 5 miles north of Pompeys Pillar National Monument. The monument, on the far side of the Yellowstone River, was not considered threatened.

The Dunn Fire started last Friday, possibly by a lightning strike in the Bull Mountains, about 40 miles north-northeast of Billings. Crews thought they had contained the blaze at about 600 acres over the weekend, until a burning tree fell across fire lines sometime Monday. That ignited grass outside the containment area that quickly spread as wind speeds increased over the next two days.

A specialized management team from Idaho is due to take over command of firefighting efforts Thursday evening, said Larry Elder with the Interagency Dispatch Center.

Elder says three helicopters from the Montana Department of Natural Resources and Conservation were lined up to dump water on the fire Thursday.