Piranhas on a Christmas Day feeding frenzy have injured some 60 people in the Argentine city of Rosario, officials say.

Those injured in the frenzy on Wednesday by the sharp-teethed fish included a girl who lost part of a finger, Health Undersecretary Gabriela Quintanilla told reporters on Thursday.

Quintanilla said the incident occurred off the coast of Rosario, some 310km north of Buenos Aires.

A medical official, Gustavo Centurion, said it began mid-morning on Christmas Day and was “very aggressive.”

“There were some people that the fish literally had torn bits of flesh from,” he said.

The region has been hit by a heat wave with temperatures soaring to some 38 degrees Celsius prompting thousands to seek relief in the waters of the Parana River, which is packed with carnivorous fish.

Officials said the unusually warm weather also was apparently responsible for the fish congregating on the river’s surface.