(Source: YouTube/CosmosNews)

At least 70 swimmers were injured in a river in Argentina when a school of carnivorous fish believed to be the piranha's cousins attacked on Christmas Day.

On December 25, thousands of people were cooling off in the Parana River in Rosario when swimmers suddenly raced out of the water with bleeding wounds. Other were shouting for help as parents of children who were still in the river dragged them to safety. The Argentine river is 300km away from Buenos Aires.

According to Argentine authorities, a school of palometa fish was blamed for the "exceptional" attack. Paramedics on the scene reported that dozens of people had injuries in their extremities while others, some children, had severed fingers or toes. Before police closed off the beach, coastguards called paramedics to treat those who were the most seriously injured.

Federico Cornier, director of lifeguards in Rosario, said swimmers in the river suddenly complained of bite marks on their hands and feet. The river has become a popular destination as people cooled down in 100 degrees Fahrenheit weather. Mr Cornier explained that the palometa fish was a "type of piranha" with big and sharp teeth.

The piranha attack on Christmas Day was "not normal," Mr Cornier told BBC. Alberto Manino, a paramedic who helped treated the victims, said some children lost entire fingers.

The Independent reported that a 7-year-old girl lost part of her fingers while a boy had an open fracture on his hand.

The feeding frenzy of piranha-related fish was described by Gustavo Centurion as "very aggressive." The carnivorous fish may have wandered into the area because they were attracted to bait left by fishermen at the Parana River beach.

The last serious attack blamed on palometas happened in 2008 with 40 swimmers injured. Ricardo Blasatti, a spokesman for the local government, was quoted by The Mirror UK as describing the attack as "rare."

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