Image: Namibian Broadcasting Corporation via YouTube

More than 100 hippopotamuses have mysteriously died in Bwabwata National Park in the northeastern region of Namibia.

Shocking footage from the scene shows the upturned bodies of the dead hippos floating in water, in some cases surrounded by vultures. Park authorities are investigating the situation, but they believe an anthrax outbreak may be to blame for the sudden deaths, which began on October 1.

While most people probably think of anthrax as the deadly white powder often sent in the mail, it’s actually an infection caused by the bacteria Bacillus anthracis. The bacteria can be found in soil, where it can survive undetected for decades.

Animals like hippos, elephants and water buffalos are particularly vulnerable to getting infected while grazing. Once the bacteria enter their bloodstream, they quickly multiply and can cause extreme illness or even death within days.

Image: Namibian Broadcasting Corporation via YouTube

In fact, this wouldn’t be the first time anthrax has killed hippos.

“This is a situation that we have seen before,” Director of Parks and Wildlife Management Colgar Sikopo told local news site New Era. “It mainly occurs when the level of the river is so low.”

About 200 hippos died from an outbreak in Uganda’s Queen Elizabeth National Park in 2004, reports National Geographic. And in 2010, another 82 hippos and nine buffalos succumbed to an anthrax infection in the same park.

Officials say the disease isn’t likely to spread because the dead hippos are in a remote section of the park. However, the more than 5,000 people who live in Bwabwata have been warned not to eat the meat or come in contact with the animals.

See video footage below: