Authorities said they finished two rounds of testing on residents of Pok Tat House in Pok Hong Estate at around 2pm.
There were four indeterminate results, while 14 households did not answer the door.
The government said it has supplied food packs and personal protective equipment to those who’ve tested positive, as they wait to be sent to hospitals or isolation facilities.
Meanwhile, the government said that at around 2.30pm, it locked down Chung Wo House in Chung On Estate, Sha Tin, for overnight testing.
Authorities said they aim to finish the operation at around noon on Tuesday, but it may be extended depending on the test results.
Anyone else who was in the building for more than two hours between February 8 and February 21 must also get tested by Wednesday.