The five-year-old brother and the eight-year-old sister perished at the scene on Saturday in Berlin Township, Michigan.
Six adults and three children—some with potentially fatal injuries—were flown to hospitals in helicopters or ambulances.
Private automobiles were used to transport some of the injured people to hospitals after they received first aid at the spot.
The 66-year-old driver of the car, according to the news, was involved in a collision that sent her flying 25 feet into the structure.
The incident happened at Swan Creek Boat Club in about 3 p.m.
