Residents of Yee Lai Court, or Block 10 of South Horizons, will undergo mandatory coronavirus tests.
“As a confirmed case with unknown source is detected in Block 10… the risk of infection in the relevant area is accessed to be likely higher,” a government spokesman said.
The patient is a woman, 23.
The “ambush lockdown” began at 8:30pm. Residents are required to undergo testing before 2am and stay at home until the results come back.
The lockdown is expected to be lifted at about 8am on Saturday.
Health authorities reported nine new infections on Friday, all but one of which imported.