Hundreds of minks that were killed in Denmark to prevent the spread of the coronavirus have reportedly risen from their shallow graves after gases built up inside their bodies.

“The gases cause the animals to expand and in the worst cases, the mink gets pushed out of the ground,” Jannike Elmegaard of the Danish Veterinary and Food Administration said, according to the Associated Press (AP). Emegaard said “a few hundred” animals rose from the ground, according to the report.

The mink are buried in trenches that are layered. The first set of mink are buried in a grave 8.25 feet deep and 10 feet wide, the AP reports. Once the first layer of mink is buried, they are covered with chalk before another layer is added again. The second layer is also covered with chalk and then again with dirt, according to the AP.

Elmegaard told the AP he assumes that the top layer of mink resurfaced because the soil is reportedly sandy.

“We assume it is the mink that were in the upper layer that pop up,” Elmegaard told the AP.

“Had the earth been more clayish, then it would have been heavier and the mink would not have resurfaced,” he continued.

The Danish environment ministry said it was a “temporary problem tied to the decaying process,” noting the area would be monitored 24 hours a day until a fence is built “to avoid potential problems for animals and humans,” according to The Guardian.

Danish authorities began killing minks after 63 mink farms reported coronavirus outbreaks. (RELATED: Tiger Tests Positive For Coronavirus At Tennessee Zoo)

Veterinarians and farmers have begun culling at least 2.5 million minks in northern Denmark, after coronavirus has been reported in at least 63 farms. https://t.co/MhoGcKk5Vq

— AP Europe (@AP_Europe) October 12, 2020

Following mass outrage over the killings, Denmark’s Minister of Food, Agriculture and Fisheries, Morgens Jensen, offered his resignation after the order to kill minks caused outrage since health minks were also being slaughtered, despite the legislation not authorizing it.

In Denmark the agriculture minister resigned over the recent order to cull 17million mink, which had no legal basis. pic.twitter.com/wsFz6Dksmi

— Sen. Muluvi Mutua, EBS (@Muluvi) November 22, 2020