China has sealed off parts of its northwestern city of Yumen after a resident died of bubonic plague last week, state media has reported.
It said 151 people who came into direct contact with the victim were also placed in quarantine.
A 38-year-old victim was infected by a marmot, a wild rodent, and died on July 16.
Several districts of the city of about 100,000 people in Gansu province were subsequently turned into special quarantine zones, Xinhua said.
None have so far shown any signs of infection, the news agency said.
The city had set aside $161,200 for emergency vaccinations, the Jiuquan Daily, a local newspaper, said on Tuesday.
The plague is a bacterial disease spread by the fleas of wild rodents such as marmots.
While the disease can be effectively treated, patients can die 24 hours after the initial infection, the World Health Organisation says.
Outbreaks in China have been rare in recent years, and most have happened in remote rural areas of the west.
China's state broadcaster said there were 12 diagnosed cases and three deaths in the province of Qinghai in 2009, and one in Sichuan in 2012.
Beijing's disease control centre sought to dispel worries about a wider outbreak, saying on its website that the risk of the disease spreading to the capital was minimal.