Four people were pulled from the water at Lake Poinsett Monday afternoon after the boat they were in capsized.
Authorities say the 911 call came in around 2:20 p.m. When Hamlin County sheriff's deputies arrived, they found four people clinging to a boat about 200 yards offshore.
A couple of nearby residents jumped in their boat and rescued the two adults and two juveniles. All four were taken to the hospital as a precaution.
Authorities say a large wave caused the boat to capsize, and that the family was in the water for about an hour before they were rescued.
The incident is being investigated by the Hamlin County Sheriff's Office and the South Dakota Game, Fish and Parks.
The Lake Norden Ambulance, Hamlin County Emergency Management, Watertown Ambulance, Performance Towing and the Codington County Search and Rescue were also on scene.