A man has plunged head-first over Niagara Falls and survived.
The Niagara survivor, photographed by witness Terry McMullen
The man, whose name has not been released by police, is the first person known to have gone over the famous north American waterfall without any protective device and lived.
Bystanders watched in astonishment as the man floated by in the Niagara River and plunged 180 feet (54 metres) down the Canadian side of the falls - known as the Horseshoe Falls, the Associated Press reports.
They described seeing him jump into the water and disappear over the edge of the falls without making a sound.
His motivation is not yet known.
Eyewitness Brenda McMullen told a local television station: "He just looked calm. He was gliding by so fast. I was in shock really that I saw a person go by."
Brenda's husband Terry took photographs of the man moments later, after he emerged from the water at the base of the falls and pulled himself onto the bank.
Television footage showed officers from the Niagara Parks police leading away a bare-chested man in handcuffs, his face covered by a blanket.
A police statement said there appeared to be no evidence of foul play, but it did not mention the man's name or shed any light on why he made his perilous journey.
About a dozen people have gone over the Falls since 1901, usually inside a barrel or some other kind of protective device.
About half of them have survived.
In 1960, a seven-year-old boy wearing a lifebelt survived a trip over the Horseshoe Falls after being thrown into the water in a boating accident.
The falls straddle the border between the United States and Canada, with the US side - known as the American Falls - considered the rockier and more dangerous of the two.
No-one has ever survived a plunge over the American Falls.