China has put 13 million people in the city of Xi'ian into lockdown in a bid to control a spike in coronavirus cases.
It comes just weeks before the country hosts the Winter Olympics in Beijing - roughly 621 miles to the west of Xi'an.
Meanwhile, it is unclear whether the surge in outbreaks are being driven by the new Omicron variant or the far more common Delta.
China has recorded just seven Omicron cases - four in the southern manufacturing centre of Guangzhou, two in the southern city of Changsha and one in the northern port of Tianjin.
The country has also been dealing with a substantial outbreak in several cities in the eastern province of Zhejiang near Shanghai, although isolation measures there have been more narrowly targeted.
China's measures to drive new COVID transmissions to zero have led to frequent lockdowns, universal use of face masks and mass testing.
While the policy has not been entirely successful, leading to massive disruptions in travel and trade, Beijing credits it with largely containing the spread of the virus.
The Xi'an restrictions are some of the harshest since Wuhan was locked down last year after the first cases of COVID were recorded.
One person from each household will be allowed out every two days to buy household necessities.
Xi'an reported another 63 locally transmitted cases on Thursday, pushing the city's total to at least 211 over the past week.
Xi'an is the capital of Shaanxi province, famed for its imperial relics, as well as a major centre of industry.