A second man has died of pneumonic plague in a remote part of north-west China where a town of more than 10,000 people has been sealed off.
The 37-year-old victim was a neighbour of the first person to die from the plague, a herdsman aged 32 in Ziketan in Xinghai in Qinghai Province.
The sparsely populated area is mostly inhabited by Tibetans.
Pneumonic plague, which attacks the lungs, can spread from person to person or from animals to people.
Bubonic plague is spread by flea bites or contact with infected animals
Pneumonic plague, caused by the same bacterium, can spread between humans
Pneumonic plague, affecting the lungs, can kill within 24 hours
Almost all cases curable if diagnosed in time
A spokeswoman for the World Health Organization, Vivian Tan, said an outbreak such as this was always a concern, but praised the Chinese for reacting quickly and for getting the situation under control.
A BBC correspondent in Beijing, Michael Bristow, says that unlike in the past the authorities are being very open about this outbreak.
Local officials in north-western China have told the BBC that the situation is under control, and that schools and offices are open as usual.
But to prevent the plague spreading, the authorities have sealed off Ziketan, which has some 10,000 residents.
About 10 other people inside the town have so far contracted the disease, according to state media.
No-one is being allowed leave the area, and the authorities are trying to track down people who had contact with the men who died.
Initial symptoms of pneumonic plague include fever, headache and shortness of breath.
The local health bureau has warned anyone with a cough or fever who has visited the town since mid-July to seek medical treatment.
Health officials in Qinghai have been concerned about pneumonic plague for some time.
In February, they said they had sent out 55 teams across the province to help monitor and control the disease.
One Chinese media report said this was the third outbreak of the disease in Qinghai within the last 10 years.
It looks like the authorities have got the situation under control
WHO spokeswoman in China
According to the WHO, pneumonic plague is the most virulent and least common form of plague.
It is caused by the same bacteria that occur in bubonic plague - the Black Death that killed an estimated 25 million people in Europe during the Middle Ages.
But while bubonic plague is usually transmitted by flea bites and can be treated with antibiotics, pneumonic plague is easier to contract and if untreated, has a very high case-fatality ratio.
The WHO was informed on Saturday of the outbreak but has not been asked for help.
"When it comes to outbreaks of the plague it's always quite worrying, but it looks like the authorities have got the situation under control," said WHO spokeswoman Vivian Tan.
"This area is quite remote and the population is very small so this should make it easier to contain."