A Bengal tiger snatched a helpless fisherman off his boat Thursday as his children watched in horror, and then dragged his body into a mangrove swamp in east India.

The man, Sushil Manjhi, is presumed dead.

Sushil and his son and daughter were crab fishing in the Sunderbans National Park when the attack happened. The tiger leapt onboard and clamped its jaw around Sushil's neck, his son Jyotish said.

The tiger "quickly flung my father on his back and gave a giant leap before disappearing into the forest," Jyotish told the Associated Press (AP).

Though he and his sister furiously beat the animal with sticks and a knife, they were no match for the strong tiger - an animal that usually weighs 550 pounds and is 10 feet long.

Many poor Indian villagers like Sushil fish for crabs in the protected reserve - even though it's off limits - to sell in nearby markets. But this attack underlines the risk such fisherman take when they wander into the territory of wild predators.

The national park is one of the largest reserves for the royal Bengal tiger, according to the AP. Thursday's attack was the fourth deadly assault by a tiger this year in the Sunderbans, wildlife officials said.

According to tigerwidows.org, named for the women whose husbands have been killed by tigers in this region, about 250 Royal Bengal tigers roam freely in the Sundarbans - a network of estuaries, tidal rivers and creeks spread over roughly 3,860 square miles (10,000 square km), about three-fifths of which is in Bangladesh, according to the Encyclopaedia Britannica.

Bengal tigers are primarily found in India, the World Wildlife Fund reported, but smaller populations exist in Bangladesh, Nepal, Bhutan, China and Myanmar as well.

There are now fewer than 2,500 left in the wild, and so the Sunderbans habitat is crucial for their survival.