One of the boys was under water for about 13 minutes before firefighters could locate him.
Tim Rutledge was pinned underneath his rig after he tried to clear ice off the brakes.
Infants and elderly most at risk.
55-year-old John Freskos of Clayton was found about 6:30 a.m. Saturday in a grassy area, about a mile from his home.
The three victims were last seen alive Saturday afternoon, hiking along the Ozark Trail. By the next day, they were dead.