More than 300 endangered sea turtles were found dead off the coast of Mexico in an abandoned illegal fishing net.
The Mexican government's Federal Environmental Protection Agency said the olive ridley sea turtles drowned after getting caught in the net.
The Coordinator for Civil Protection in San Pedro Mixtepec, Jose Antonio Ramirez Garcia, said the net could have been cast by a tuna fishing ship.
"The fishermen tell us that [the net] is not from around here," Mr Garcia said.
"It could have been abandoned by a tuna fishing ship without reporting it lost, causing the death of these animals which are in danger of extinction."
Olive ridley turtles, which lay their eggs on the beaches of a number of Mexican states between May and September, are considered to be facing a high risk of extinction in the wild.
Experts suspect asphyxiation, toxic algae or hooks attached to the net could have killed the animals.
The cause of the deaths is still under investigation.
The government's special prosecutorial office for crimes against the environment is leading the probe.