Nanjing, the capital city of Jiangsu province, reported nine locally transmitted cases and five asymptomatic cases as of 1 pm Wednesday.

It also said that three other samples collected from staff at the Lukou International Airport tested positive for COVID-19 and needed further diagnosis by medical experts.

All the confirmed cases are cleaning workers of the Lukou International Airport, located in Nanjing's Jiangning district.

The city has upgraded two communities and two villages in the district from low-risk to medium-risk areas for COVID-19 on Wednesday morning.

All the residents living in Jiangning have started receiving nucleic acid tests since 9 am Wednesday. As one of the downtown districts of Nanjing, Jiangning has a population of more than 1.9 million.

With the upgrade, Nanjing has suggested people not leave the city. Anyone that has to leave the city must present a negative nucleic acid test result taken within 48 hours since Wednesday.

The city's education bureau has notified after-school tutoring groups to suspend classes.

Nanjing also reported two imported cases, both from Argentina, on Wednesday.