Roughly 2,500 seals were discovered dead on Sunday along the Caspian Sea in the south Russian province of Dagestan. The number continues to grow as investigators count the bodies, according to the Ministry of Natural Resources of Dagestan. “Bodies are found at different locations,” the ministry wrote in an announcement to its Telegram channel. “Especially large numbers are in the Yuzbash area, as well as between the mouths of the Sulak and Shurinka rivers.” Local authorities say it’s unclear what caused the mass death, but claim it was likely natural causes, according to the Associated Press. Exact causes will be determined after lab studies are performed on the animals, according to the Ministry. The head of the Caspian Environmental Protection Center, Zaur Gapizov, said it was possible that the seals died a couple of weeks ago, adding that there were no indications that they had been poached, the outlet reported. Other Russian agencies, including the Federal Fisheries Agency, inspected the coastline but did not report any sightings of possible pollutants. Anywhere between 70,000 and 300,000 seals are believed to live in the inland sea, depending on local statistics.