Health authorities on Wednesday sealed off Tsui Wo House in Tai Po for an overnight lockdown, after detecting preliminary positive coronavirus cases there.
Residents will have to stay home and get tested. The operation in Tai Wo Estate is expected to end at around 7am tomorrow.
Anyone who stayed there for more than two hours since last Saturday also need to get tested.
The government also locked down a building in Shek Yam East Estate in Kwai Chung, after detecting a positive case and several preliminary positive cases which may involve a mutant strain.
The lockdown operation on Yam Yue House is expected to last until 7am on Thursday.