Tens of thousands of dead fish were found washed up on the shores of a Mexican reservoir, and a local mayor is accusing a cattle food plant of causing the contamination that killed the fish.

The fish were asphyxiated due to hundreds of liters of molasses allegedly poured into a canal that feeds into the Hurtado reservoir, said Emeterio Corona, the mayor of the nearby town Acatlan de Juarez, according to several media reports.

Nearly 200 families are said to feed themselves by fishing in the reservoir. The event, which is estimated to have killed at least 500 metric tons of fish, puts the livelihood of an entire community at risk.

"The environment and the sustenance of everybody [in the community] was damaged," Corona said, according to the APF. "What will they live off? I'm outraged. This is a tragedy."

A video shows men using garden rakes to collect the fish on shore and mountains of the dead fish being dumped into a truck by a front loader. Mostly carp and bream were killed in the reservoir, which is in the state of Jalisco in western Mexico.

Viscous, brown molasses is a byproduct of refining sugarcane and beets for cattle to eat. The cattle feed plant was reportedly operating without a permit. 

The company responsible for the dumping has not been named.