They were among around 2,100 residents tested in Block 21 of the Shek Kip Mei Estate since Friday. The lockdown had been due to end on Saturday but was extended because of the high number of cases.
The government said it would distribute disinfection products and surgical masks to people testing preliminary positive, as they wait for follow-up arrangements.
Results for six people are uncertain and health officials said these cases will be followed up accordingly.
Officials also visited about 470 households, among which 30 did not answer the door.