FOSSIL, Ore. -- A small new wildfire in Wheeler County was threatening structures Thursday night, with a high potential of spreading, Central Oregon fire officials said.

The Rosenbaum Fire (Incident 722) was reported around 7:30 p.m., four miles north of Service Creek, burning in grass and timber.

"The fire is approximately 5 acres, with creeping and torching with a high rate of spread potential," the initial report said, adding that winds in the area were "light and variable."

Before 10:30 p.m., Watch Duty said the fire was 100 acres, according to the National Interagency Fire Center.

Engine, dozers and added crews were ordered to the scene. The cause was under investigation.