RELIANCE, S.D. -

A weekend grass fire in Lyman County shut down a South Dakota highway for five hours.

Authorities believe a spark from a car fire caused the Saturday afternoon blaze near Reliance. It burned an estimated 784 acres, or a little more than a square mile.

County Sheriff and Emergency Manager Steve Manger says no one was hurt, and fire crews with the help of area farmers were able to contain the blaze before it reached any buildings. However, a 3-mile stretch of South Dakota Highway 47 was shut down for five hours after the fire jumped the roadway.

More than 50 firefighters from seven fire departments responded.