Nigeria, April 9 -- At least 50 hippos and other large animals have been killed by anthrax poisoning in Virunga National Park, the oldest African park located along Eastern Congo.

The Virunga Park director, Emmanuel De Merode, disclosed this on Tuesday.

The animals were found floating motionless along the Ishasha and Lake Edward River. Images shared by the national park showed them lying on their backs or sides on the banks of the river.

About 25 hippopotamus bodies were seen floating in the lake.

According to the park director, some buffalo have also been killed. He said although tests have confirmed that the deaths were caused by anthrax poisoning, the exact cause of the poisoning is still unknown.

Anthrax is an infectious disease ...