Part of a city in north-west China has been sealed off and dozens of people placed in quarantine after a man died of bubonic plague, state media say.

The man died in Yumen city, Gansu province, on 16 July. A total of 151 people have been placed under observation, Xinhua news agency says.

Authorities have isolated a part of the city centre and three sections of Chijin town which is an hour away.

The man was believed to have caught the infection after contact with a marmot. Marmots are large, squirrel-type rodents that live in mountainous areas. The victim is reported to be a 38-year-old man who had fed a dead marmot to his dog.

The deputy head of the hospital where the man died told reporters that the victim had arrived with an increased heart-rate and seemed to be slipping into shock. The hospital has since been quarantined.