The government has imposed lockdowns on two buildings in Tseung Kwan O and Kwun Tong, requiring residents to get tested for Covid-19 overnight.
Authorities sealed off Block 5 of On Ning Garden in Tseung Kwan O on Friday night, saying preliminary positive infections have been reported at the building.
Officials also locked down Sau Yee House of Sau Mau Ping Estate in Kwun Tong after sewage samples there tested positive for the virus.
The operation in Tseung Kwan O is expected to be completed at 5pm on Saturday while the one in Kwun Tong will finish at around 1pm.