An apparently distraught man jumped into Niagara Falls and survived the 180-foot plunge, then resisted rescue attempts before he eventually was pulled from the icy water to safety, Canadian police said.
The man, believed to be in his late 30s, was semiconscious when he was taken to a hospital. He lapsed into unconsciousness and was listed in critical condition.
Niagara Parks Police Chief Doug Kane said the man "voluntarily entered into the water and refused medical assistance at the bottom".
He said the man was suffering from hypothermia and a head injury. Police were unable to get any information from the man because of the effects of the near-freezing water.
A witness called police and told them a man had jumped into the Horseshoe Falls, one of Niagara Falls' three waterfalls. A short time later, the man was seen near the base of the falls.
Specially trained falls rescue crews tried to assist the man, but he swam away from them toward the middle of the river, Mr Kane said.
A private helicopter was called in and got close enough to the victim so that wind from its blades forced him close enough to shore for rescuers to reach him.
"He wasn't cooperative," pilot Ruedi Hafen, owner of Niagara Falls Helicopter, said. "He didn't try to be helpful. We had a sling on him and he got out of it."
Rescue crews said the man was in the water for about 45 minutes and spent much of that time resisting attempts to help him.
Firefighter Todd Brunning and another rescue worker swam about 60 yards from shore, grabbed hold of him and hauled him in, Niagara Fire Captain David Belme said.
"I was surprised he was still conscious when we got to him," Mr Brunning said. "I guess he was lucky."