Tens of thousands people in the old downtown district in Yumen, Northwest China's Gansu Province, are currently not allowed to leave town after a man died last week of bubonic plague. 

According to cncnews.cn, a news video website affiliated with Xinhua, the lives of the 30,000 people are not affected, but police have set up roadblocks at the nearest highway exit, allowing people to enter but not to leave the affected area.

In a separate feature story published on xinhuanet.com on Monday, several districts in Yumen were put under quarantine, including Laocheng district, or Yumen's old downtown district.

Once a populous area due to the oil industry, the district now has a population of about 30,000, the report said.

Xinhua quoted the local government as saying that Yumen has seen at least five cases of plague over the past years and the current case is an isolated incident.

The 38-year-old victim was said to have approached a dead marmot, a small furry animal which lives on grasslands and is related to the squirrel.

The victim allegedly chopped it up to feed his dog but developed a fever the same day. He was taken to hospital after his condition worsened and died last Wednesday.

 "The city has enough rice, flour and oil to supply all residents for up to one month," China Central Television said.

Shanghai-based Oriental Morning Post reported earlier that quarantined districts, such as Laocheng and Chijin, have launched a nine-day traffic control system since Saturday.

Bubonic plague is categorized as a "Class A infectious disease … [which is] the most serious under China's Law on the Prevention and Treatment of Infectious Diseases," said Xinhua.

Bubonic plague is a bacterial infection, also infamously known as the "Black Death," a virulent epidemic of the disease that killed tens of millions of people in 14th century Europe.

Primarily an animal illness, it is now extremely rare in humans.

Modern antibiotics are effective in treating bubonic plague, but without prompt treatment it can cause serious illness or death.