A British man on holiday in Australia grabbed a shark by its tail and tried to drag it away from people playing at the edge of the sea.
The man, named as grandfather Paul Marshallsea, was on a beach north of Brisbane in Queensland when a siren was sounded to warn of a shark in the water.
Marshallsea, 62, from Merthyr Tydfil in South Wales, ran to the shoreline and grabbed the shark by the tail.
The incident was captured by a local news crew, and footage shown on Sky News shows him wrestling the fish in the shallows and trying to guide it towards deeper water.
But as the shark thrashed to free itself, Mr Marshallsea fell into the waves, and the creature turned and snapped its jaws just inches from his leg.
Marshallsea said: "It just missed me with a bite, which was a fraction away from my leg. A shark that one minute ago was so docile now just nearly took my leg off."
Marshallsea, who was helped by another man, said his "instincts took over" when he saw a number of young children in the water, the Daily Mirror said.
"It's shallow for about six yards where the shark was and a lot of babies and toddlers splash about there," Marshallsea said. "It could have been very nasty.
"My instincts took over and I grabbed the shark by the tail. I know it was dangerous but it almost looked beautiful. You have to respect a beautiful animal.
"When I dragged the shark to just over knee-deep, he turned on me and just missed me with a bite. It nearly took my leg off in a split second. It was that quick."
The incident, which was reported to have happened at Bulcock Beach in Caloundra, about 55 miles (88km) north of Brisbane, was witnessed by Australian lifeguard Luke Turner.
Turner told Sky News he and a colleague had been following the shark around all morning before it swam into the bathing area.
"We chased it away and called in the helicopter for back-up. Then a few hours passed and it happened to come back in.
"A British tourist jumped into the water as well as a wildlife rescue guy, and they pulled it back out to sea.
"Me and my partner proceeded to follow it back out through the channel while it swam back out to sea."
The shark was reported to have been a 6ft (1.8m) dusky whaler shark, a species which rarely attacks humans.
Wildlife experts reportedly said the shark may have been so close to shore because it was sick or injured and so was stressed and disorientated.