Only about two dozen buildings were left standing after the tornado swept through Spencer, 45 miles west of Sioux Falls, on Saturday night. About 150 people were injured, many of them elderly.
The tornado was part of a swarm of thunderstorms that battered states in America's Midwest on Saturday evening and early yesterday. Winds were gusting at up to 100mph.
More than 900,000 homes and businesses lost power in Minnesota, Wisconsin and Michigan, and five more deaths were blamed on the storms.