"This is not normal," director of emergency services in the city of Rosario, Federico Cornier, said on Argentinian TV
. "It's normal for there to be an isolated bite or injury, but the magnitude in this case was great."
Cornier called the fish "A type of piranha, big, voracious and with sharp teeth that can really bite."
Biting fish attack Argentina swimmers
The mass attack happened at the beaches at the Parana River, near Rosario, which is about 185 miles (300 km.) from Buenos Aires. Reporter Alejandro Lifschitz of Reuters
wrote that a holiday heatwave in the area had many locals seeking shelter from the temperature in the water. Because of that the fish had a many potential victims to choose from.
It's not uncommon for a biting fish to get teeth into a swimmer at beaches in the country, but a gang-like attack like the one Christmas Day at the Parana River beaches is rare.
"This is an exceptional event," Cornier said.