Shijiazhuang in Hebei province increased static management on Sunday after a rise in the number of COVID-19 cases in the last few days.

Mass nucleic acid testing was carried out in nine districts on Saturday, detecting 30 positive results among nearly five million residents, and two positive sample tubes taken from multiple persons, according to the city's leading group for countering the epidemic.

Mass testing the previous day turned up 18 positive cases, all in Qiaoxi district-the epicenter of the current outbreak, it said.

To reduce activities and cut down transmission, Shijiazhuang began static management in its four districts-Qiaoxi, Yuhua, Xinhua and Chang'an-on Sunday afternoon for a period of three days, according to the group.

Residents in the districts are required to stay home and all but essential businesses were suspended. The city also halted subway operations on Sunday afternoon.

Mayor Ma Yujun, presided over a meeting to discuss the epidemic on Saturday. He said that residential communities should dispatch working groups to provide services to residents so that they face minimal disruption while confined at home.

With the Mid-Autumn Festival holiday, which falls on Sept 10 drawing near, residents have been advised not to leave the city and those outside should not enter unless it is absolutely necessary.

The city's current outbreak started over a week ago on Aug 18 when three asymptomatic cases were reported, all passengers on the same train from the Tibet autonomous region to Beijing.

More cases began to emerge on Thursday when 10 asymptomatic cases were reported. Facing a new peak, the city started carrying out mass nucleic acid testing on Thursday.

According to the analysis of the positive tests and gene sequencing results, the current outbreak has been caused by Omicron subvariant BA.2.76, which is homologous to the cases detected in Tibet.

So far, Shijiazhuang has designated seven high-risk areas, including four in Qiaoxi district.

The province reported 29 asymptomatic cases on Saturday, mainly in the capital city, Shijiazhuang, according to the provincial health commission.

As of Saturday, there was one confirmed and 93 asymptomatic cases.

In the past few days, other cities in Hebei have also reported sporadic cases, including Langfang, Chengde, Baoding and Xingtai.