A commercial structure in Sun Prairie caused $15,000 worth of damage Saturday morning. Sun Prairie Fire & Rescue said the fire started after discarded rags were left near flammable materials. The fire happened on the 2000 block of Terra Court. A delivery service saw smoke inside the building and called Dane County Public Safety Communications around 9:30 a.m. Fire crews arrived on the scene in just two minutes. They located active fire involving construction materials inside the building and were able to successfully put out the fire without it spreading and without any injuries.