Some 158 tourists from countries including Sweden, South Korea, Germany and Russian Federation are now reportedly waiting for the all-clear to be given so that they can leave the town.
The marmot is known to carry Yersinia pestis, the bacteria which causes the bubonic plague.
Some people ignore the warnings as they believe that consuming the innards of the large rodent is good for their health.
Shortly after their death, regional authorities imposed a six-day quarantine on the western Bayan Olgii province, preventing nine tourists from Russia, Germany, and Switzerland from leaving, AFP reported.
In the 14th century, the Black Death led to about 50 million deaths in Africa, Asia and Europe.
However there is no inter-human transmission of bubonic plague, according to the World Health Organisation (WHO).
Cases are very rare today but can be deadly unless sufferers are treated with antibiotics.
Sebastian Pique, a 24-year-old American Peace Corps volunteer who has lived in the region for two years, said he and the tourists were invited to the governor's office on Friday to be informed about the situation.
Reports say a quarantine was declared last week, but lifted on Monday. Pneumonic plague, which is more severe but less frequent, spreads to the lungs and can be transmitted via coughing.
Bubonic plague is the most common form of plague and is caused by the bite of an infected flea.