BRASILIA:Carnivorous fish attacked bathers in a river in southern Brazil, leaving about 20 of them with bite wounds on their hands and feet, a news website said Monday, citing lifeguards.

The unusual attack occurred Sunday when a school of palometas, a species of piranhas, surprised hundreds of tourists bathing at a beach in Toropi, in the state of Rio Grande do Sul.

Lifeguards told the G1 website that 20 of the bathers suffered cuts on their hands and feet and were treated on the scene.

Firefighters said low water levels in the river, resulting in scarce food sources, may have prompted the feeding frenzy.