One person was treated for hypothermia Sunday afternoon after falling through a Sauk County lake's ice, officials said. The Delton Fire Department said it responded to a report of four people who had fallen through the ice on MIrror Lake at 12: 15 p.m. while ice fishing. When crews arrived, all four people had pulled themselves from the water and the three adults were lying on the ice crawling toward shore. The ice fishers had broken through the ice about 400 feet from shore near a public boat landing off Lakeview Road, according to a release.