Now under tight restrictions and mass testing, the city of Shijiazhuang, just 300km southwest of Beijing, has reported 50 new locally transmitted cases.
Chinee state media reported the provincial capital, which has a population of 11 million, had the majority of the new cases of patients confirmed with the virus which totalled 52, Al Jazeera reported.
Travel was restricted to the city and schools closed after authorities detected a cluster of 20 new cases overnight earlier in the week.
The total number of new COVID-19 cases for all of mainland China stood at 63, compared with 32 reported a day earlier.
This is the highest number in a single day since July last year.
Ten major highways leading into Shijiazhuang have been closed, a long-distance bus terminus was shut down and all train ticket sales into Beijing were halted.
Chinese state broadcaster CCTV showed a small crowd gathered outside a railway station in Shijiazhuang being directed by medical staff in full hazmat suits and protective wear.
“I did the nucleic acid test last night but don’t have the results yet. Without it I can’t leave the city,” a young woman told the channel.
One district of the city, the village of Xiaguozhua, has been declared high risk and sealed off and tens of thousands there tested for the virus.
Infections are believed to have been traced to social events like funerals and weddings in Xiaguozhuang.
Three officials in the district have been “punished for negligence in COVID-19 intervention”, the China Daily reported.
Any gatherings or visits between relatives are now banned in the village and police have set up roadblocks on any routes out of the county.
China has taken aggressive measures to stamp out any clusters of new cases and prevent a second wave of the outbreak, starting in the central city of Wuhan where coronavirus is largely thought to have originated in late 2019.
The total number of confirmed COVID-19 cases in mainland China now stands at 87,278, while the death toll was unchanged at 4,634.
World Health Organisation (WHO) investigators have been denied access to Wuhan, banned by Beijing.
The independent WHO probe, which is expected to take four to five weeks, is expected to hold China accountable for the COVID-19 pandemic, which has killed more than 1.8 million worldwide