Officials moved in at Blocks 5 and 7 of the Laguna City estate on Sunday evening, ordering people to take a test by 2am in the hope of being able to allow people to leave for work from 7am on Monday morning.

People who could show a negative test result or a bracelet showing that they'd been tested were allowed to leave at about 7:30am on Monday. Government workers on site were still carrying out what was described as a law enforcement operation to find people who hadn't taken a test.

Officials said they had tested 460 people at eight testing station as of 2:00am without finding any new cases. They visited 394 homes, getting no answer at 60 of them, some of which may have been vacant or home to people who had already tested positive or been sent to quarantine.

Meanwhile, the administration condemned an attack on a government worker taking part in the testing exercise inside the restricted area. It sent condolences to the injured colleague and said people under mandatory testing should cooperate.

Laguna City emerged as an area of concern last week, with officials ordering a partial evacuation of Block 5 after 10 residents and two staff were diagnosed with the virus. Flat E on each floor was evacuated after people on several floors fell ill, which experts said indicated vertical transmission.

The government held the first of what Chief Executive Carrie Lam called "ambush-style" lockdowns in Yau Ma Tei on Tuesday, finding one case. A lockdown in North Point on Thursday did not find infected people.