Beijing's Haidian district reported Sunday one person has tested positive for COVID-19 and that has triggered an emergency response, according to the official WeChat account of the district.

Prior to this case, Beijing had reported no new locally transmitted, asymptomatic or suspected cases of COVID-19 for six straight days.

"The residential building where the positive case lives has been classified as a high-risk area for COVID-19," according to the announcement.

All people living in the residential community are undergoing nucleic acid tests.

The person, who arrived in China from overseas on July 20, had completed the 10-day centralized quarantine outside Beijing and came back to the capital via high-speed train on Saturday.