Part of a city in Gansu province remained sealed off yesterday after the death of a local man from pneumonic plague last week.
About 30,000 people living in the old town of Yumen in the northwestern province were not being allowed to leave the area to prevent any spread of the deadly disease, state broadcaster China Central Television said.
The nine-day quarantine period ends tomorrow.
All people, vehicles and objects have been banned from exiting the old downtown area of the city and another township called Chijin, where the man lived and was infected, the CCTV report said.
No further cases had been reported by yesterday.
Authorities began sealing off the area on Wednesday last week, when the patient died in a local hospital. The isolation period was set at nine days on advice from doctors, Xinhua reported.
Other reports said the 38-year-old victim had come across a dead marmot on July 13.
He is said to have chopped it up to feed to his dog, but developed a fever the same day. He was then taken to People's Hospital in Yumen after his condition worsened two days later.
Gansu's provincial centre for disease control confirmed on Thursday that the man had contracted pneumonic plague, according to Xinhua.
One of three main forms of plague, pneumonic plague is a severe type of lung infection. According to the US Centres for Disease Control and Prevention, it may develop from inhaling infectious droplets or untreated bubonic or septicemic plague after the bacteria spread to the lungs.
It is the only form of plague that can be spread from person to person, by infectious droplets.
The Gansu Legal Daily quoted local authorities yesterday as saying that no further cases had been reported among the 151 quarantined as of Saturday evening.
"Because it was diagnosed in time and dealt with appropriately, the plague has been under effective control," it said.
Local police at roadblocks on the city perimeter have been telling motorists to find alternative routes, Xinhua reported.
"The isolated areas have a food supply that can last for over 10 days," the agency quoted an official from the Yumen grain bureau as saying.
Additional reporting by Agence France-Presse