Hong Kong (AFP) Thousands of Hong Kong residents were locked in their homes on Saturday in an unprecedented move to contain the city’s worsening coronavirus outbreak.

Authorities said in a statement that a district with 16 buildings in the city’s Yao Zimmung district would be closed until all residents were tested. Residents will not be allowed to leave their homes until they receive their test results to prevent transmission.

“Persons subject to the compulsory test are required to remain at their workplaces until all persons identified in the area have been tested and test results are often confirmed,” the government statement said.

The government said the restrictions, announced at 4 am in Hong Kong, are expected to end within 48 hours.

Hong Kong has been struggling to contain a new wave of coronavirus since November. More than 4,300 cases were recorded in the past two months, nearly 40% of the city total.

Coronavirus cases in Yao Tsim Mong accounted for about half of the infections in the past week.

Nearly 3,000 people in Yao Tsimong have taken coronavirus tests so far, according to the Hong Kong government, joining the thousands of others around the crowded city of 7.5 million people who have been tested in recent days.

Police guarded access points to a working-class neighborhood from old buildings and split apartments and arrested a 47-year-old man after he allegedly attacked an officer. The man was reportedly told that he would be tested after entering the restricted area and would not be allowed to leave until he showed a negative test result.

Sewage testing in the area has revealed more concentrated effects of the virus, raising concerns that poorly constructed plumbing systems and lack of ventilation in divided units may represent a potential pathway for the virus to spread.

Hong Kong has previously avoided lockdowns in the city during the pandemic, with Leader Carrie Lam stating in July of last year that the authorities would avoid taking such “extreme measures” unless they had another option.

The government called on employers to exercise discretion and avoid cutting salaries for employees who were affected by the new restrictions and may not be able to go to work.

Hong Kong had seen a total of 9,929 infections in the city, with 168 deaths recorded as of Friday.