A 10-acre wildfire that started Wednesday afternoon on Interstate 90 westbound near Elk Heights Road is contained and controlled. The Thorp Prairie fire started at 3:37 p.m. at milepost 95. It was burning in grass and brush, according to Kittitas Valley Fire Department Deputy Chief Rich Elliott. Every available fire district in the county responded to the fire with about five fire engines and 60 firefighters. The fire was contained and controlled by 5:19 p.m.; no structures were threatened and no one was injured. A vehicle which broke down on Interstate 90 caused the fire, Elliott said. A strong breeze in the area made the fire move more quickly. The fire then burned through an elk fence and took off into nearby dry grass and sagebrush.