Students line up to take nucleic acid tests Monday at a middle school in Shijiazhuang, North China’s Hebei province. A day later, the provincial capital began a second round of Covid-19 testing for all 11 million of its residents.

A woman takes a nucleic acid test Monday on Hanzheng Street in Wuhan, Central China’s Hubei province. On Jan. 4, a person traveling from Shijiazhuang visited the street before being confirmed with Covid-19.

A bus transports villagers from Shijiazhuang’s Gaocheng district, the only high-risk area for Covid-19 in the country, to designated places where they will be isolated under medical observation.

Volunteers rest in front of a closed residential community Sunday, the day after local authorities required residents to stay at home in an effort to curb the outbreak.

A resident accepts a package through the fence of a closed residential community.

A worker in full protective gear stands guard in front of a closed road Thursday after the city was put under lockdown.

A worker examines equipment at Huoyan Laboratory, which was built to process test samples taken during Shijiazhuang’s latest outbreak.