(CNN) -- A wildfire had spread across at least 1,000 acres of Kaibab National Forest in northern Arizona by early Thursday, forcing authorities to evacuate 50 residences, the U.S. Forest Service reported.
"The high winds and low relative humidities are making fire suppression activities difficult," a statement from the service said.
Some 250 personnel were fighting the fire about 10 miles northeast of Williams. The evacuations were made from the Spring Valley area.
The cause of the blaze was not immediately known.