Hundreds of Argentines cooling off in a river near the city of Rosario have been attacked by a school of piranha-like fish.
At least 70 people were treated at clinics and emergency rooms in the area.
The attack by palometas, a type of large piranha, occurred as city dwellers attempted to escape the 38 degrees Celsius heat of Christmas Day.
"There were some people that the fish literally had torn bits of flesh from," a medical official at the scene, Gustavo Centurion, was quoted as saying by the Latin Times newspaper.
Federico Cornier, Lifeguards director for the region told reporters that the attack was unusual in the number and ferocity of the bites.
"It's normal for there to be an isolated bite or injury, but the magnitude in this case was great ... This is an exceptional event," Cornier said.
A seven-year-old girl lost a finger in the attack and dozens of people suffered serious bites to their extremities, news agencies reported.
The incident occurred along the Parana River at Rosario, about 320km northwest of Buenos Aires.
Piranhas, freshwater fish with sharp teeth, inhabit the rivers of South America. Several fatal attacks on humans have been reported in recent years, mostly in the Amazon River basin.