A fast-moving wildfire burned 40 homes across about 23 square miles of central Washington grassland, timber and sagebrush, a fire spokesman said Tuesday.

Fire commanders estimate the blaze has burned at least 15,000 acres since it started Monday afternoon east of the town of Cle Elum, Mark Grassel, a state Department of Natural Resources spokesman, said.

Fire officials said more homes were burning and under threat. So far, no injuries have been reported.

The fire crept within six miles of Ellensburg, Grassel said. Crews stopped its forward movement, although it is not contained. State officials dispatched additional firefighters and equipment to the blaze from around the state.

The Kittitas County sheriff's office warned those in the fire's path to evacuate. Few people took advantage of an emergency shelter in Cle Elum.

The fire also threatened a chimpanzee sanctuary, KING-TV reported. It burned some property but the chimps were OK, Diana Goodrich of Chimpanzee Sanctuary Northwest told the station.

The state Transportation Department said a 14-mile section of U.S. Highway 97 was closed because of the fire.