Mongolian police had seized 31 dead marmots from a vehicle that could have spread the bubonic plague.

The dead marmots were discovered on Tuesday in a vehicle traveling from a western province to the capital city of Ulaanbaatar.

Two cases of bubonic plague have been reported in the western province of Khovd since the beginning of this year, with one of the two infected people dying in mid-September, the country’s National Center for Zoonotic Diseases reported.

The bubonic plague is a bacterial disease spread by fleas that live on wild rodents such as marmots that can kill an adult in 24 hours if not treated promptly.