HOHHOT, Dec. 2 (Xinhua) -- This border city of Manzhouli in north China's Inner Mongolia Autonomous Region will launch the third round of citywide nucleic acid testing starting Thursday, local authorities said Wednesday.

The city initiated its first round of nucleic acid tests for all residents on Nov. 22, and the second round of the tests on Nov. 27 after two domestically transmitted COVID-19 cases emerged there in late November, according to the city's COVID-19 epidemic prevention and control headquarters.

A total of eight people tested positive for the virus during the second round of testing covering 203,378 residents, the headquarters said.

One street in Manzhouli was classified as high-risk area for COVID-19 Wednesday, while four other streets had been categorized as medium-risk areas.

As of 7 a.m. Wednesday, Manzhouli had 20 domestically transmitted cases, one asymptomatic case and two suspected cases. Their 1,062 close contacts have been placed under medical observation.

Epidemiological surveys and source tracing work regarding the cases are underway.