Four more locally transmitted confirmed COVID-19 cases were reported on Tuesday morning in Shenzhen, Guangdong province, according to sources with the local health authority.

The four cases, of which three are family members, were detected among close contacts with the previous cases and key persons under strict control measures, according to sources at the Shenzhen Municipal Health Commission.

The city has collected more than 22.18 million nucleic acid test samples since it reported its first two COVID-19 cases on Friday, which had a high possibility of exposure to contaminated imported goods, the authority said early on Monday.

The four newly added cases were part of the same chain of transmission as the previously confirmed cases, it added.