A 28-yearold Billings man drowned Thursday in a reservoir at a state park here. His was found by a police diver and removed from Lake Elmo at about 8:30 p.m., more than three hours after friends and family members called 911 to report that he had disappeared while swimming. The body was found in murky water about 10 feet deep, not far from where the swimmer was last seen, said Les Solheim, acting Billings fire battalion chief. The man’s name was withheld pending notification of family. Witnesses said he was among a group of four or five people floating on the lake on inner tubes and inflatable rafts. Daniel and Kelly Hood were at a picnic table near the lake’s northeast corner when they heard shouts for help. “They started screaming, Call 911!’” Kelly Hood said. She glanced at the group in the water and noticed an unoccupied inner tube slipping away from the others. Some in the group went diving after the man, Daniel Hood said. Police Sgt. Casey Hafner said the man had told friends and family he was going to swim out to one of the rafts. He made it about halfway before turning back, Hafner said. He then changed course again and went back toward the raft.