Several tons of fish have died along one of the main rivers in Brazil's Sao Paulo state after an alleged illegal dumping of industrial waste from a sugar and ethanol plant.

Several tons of fish have died along one of the main rivers in Brazil’s Sao Paulo state after an alleged illegal dumping of industrial waste from a sugar and ethanol plant, environmental authorities and prosecutors said on Wednesday.

A preliminary analysis estimates that between 10 and 20 tons of fish died on the Piracicaba River, Sao Paulo’s prosecutors said in a statement.

The initial investigation points to an “irregular discharge of wastewater” from Estiva’s Sao Jose plant in the community of Rio das Pedras and it reached a stream that flows into the Piracicaba River, prosecutors said.

Estiva, the company that operates the plant, didn’t respond to several AP requests for comment.