The Associated Press reports that Sioux Falls’ mayor, Mike Huether, called it a “100-year rain.”
Water flooded basements and the Red Cross opened a shelter for those displaced, Keloland TV reports.
No injuries were reported.
The extraordinary rains were triggered by a slow-moving front, which drew extremely moist and unstable air out ahead of it into the Plains Thursday.
Here are some unbelievable photos and videos from Twitter: