All residents in Zhuhai, Guangdong province, will undergo a nucleic acid test against coronavirus starting Monday after an asymptomatic carrier was reported early on Monday.

This round of mass testing will conclude on Tuesday, according to the COVID-19 epidemic control authority of Zhuhai.

The asymptomatic carrier flew in from Nanjing, Jiangsu province, which has reported several COVID-19 cases, to Zhuhai on July 19 and stayed in a hotel in Zhuhai. The person was sent to a quarantine hotel on July 21. The person tested negative against the virus for four times before testing positive on Sunday and was then transferred to the hospital for treatment.

Meanwhile, an office building, a hotel and two restaurants in Xiangzhou district of Zhuhai were put under a 14-day lockdown on Monday. Some other areas in Xiangzhou were placed under seven-day restrictive management. The city government pledged availability of commodities to those places.