The Grinch might be out of a job soon. 70 holiday revelers in the Argentine town of Rosario learned why they should always read the signs at the beach when they were attacked by a shoal of piranhas during a Christmas Day swim.

The attack occurred along the Parana River, where Rosario beachgoers were trying to escape scorching 100-degree temperatures. More than 20 children were wounded by the hyper-aggressive fish, with one 7-year-old reportedly losing a piece of her finger.

The attack is the worst of its kind in Rosario since 2008, when 40 swimmers were hurt. Local government spokesman Ricardo Biasatti maintains that piranha attacks remain a rarity at the city's beaches:

"This sort of event in this area is absolutely sporadic," Biasatti said. "It was the conjunction of two factors, a shoal that passed very briefly through an area full of people."

The fish were reportedly drawn to the coast by debris left by fisherman.

UPDATE: The AP is reporting that 70 people were injured. This article originally listed the number at 60 and has been updated.