The Bacillus anthracis (anthrax) bacteria may have killed more than 100 hippos this past week in Namibia, according to the country’s environmental minister, Johnson Ndokosho.

The first carcass was found on Oct. 1, and since then, many more have been spotted laying belly-up or on their side in shallow water. In an announcement made Monday, Ndokosho stated that at least 100 hippos were deceased, but the exact number is unknown because other predators like crocodiles may have feasted on some of the carcasses.

The hippos all lived within Bwabwata National Park, a remote location in northeast Namibia, situated between Angola and Botswana.

According to the Namibia Nature Foundation (NNF), there were nearly 1,400 known hippos living throughout the country prior to the mass death.

Bacillus anthracis can be found naturally in soil, and has been known to affect wildlife when water levels recede, which is what Colgar Sikopo, director of Namibia’s parks and wildlife division, believes is what happened in this instance. However, an investigation is still ongoing to determine if the anthrax bacteria is indeed the culprit.

Anthrax spores can “activate” when they enter a living organism, according to the CDC. The bacteria then multiplies and spreads throughout the body. Without proper treatment, the bacteria invasion causes death.

Similar anthrax outbreaks affecting wildlife are actually fairly common. About 200 hippos died from an anthrax outbreak in Uganda in 2004, and just last year, a thawed reindeer carcass infected with the anthrax bacteria caused an outbreak in Western Siberia. The spores coupled with an unusual heat wave resulted in the death of more than 2,000 reindeer. Seventy residents were also sent to the hospital for possible infections.

To prevent more animal deaths, hippo carcasses in Namibia are being burned and locals have been urged to not eat meat from dead animals in the area.