Thousands of Hong Kong residents were locked down Saturday in an unprecedented move to contain a worsening outbreak in the city, authorities said.

Hong Kong has been grappling to contain a fresh wave of the coronavirus since November. Over 4,300 cases have been recorded in the last two months, making up nearly 40% of the city’s total.

More Images
A general view of old residential buildings are seen in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Thousands of Hong Kong residents were locked down Saturday in an unprecedented move to contain a worsening outbreak in the city, authorities said.

Professor Yuen Kwok-yung, chair of infectious diseases in the University of Hong Kong's department of microbiology, second left, speaks to media in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Sewage testing in the area picked up more concentrated traces of the COVID-19 virus, prompting concerns that poorly built plumbing systems and a lack of ventilation in subdivided units may present a possible path for the virus to spread.

Government investigators wearing protective suits, walk in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Hong Kong has previously avoided lockdowns in the city during the pandemic, with leader Carrie Lam stating in July last year that authorities will avoid taking such “extreme measures” unless it had no other choice.

Residents wearing face masks to protect against the spread of the coronavirus, queue at a temporary testing center for COVID-19, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

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

Medical workers in a protective suits assist residents at a temporary testing center for COVID-19, in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Medical workers in a protective suits assist residents at a temporary testing center for COVID-19, in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Police officers wearing protective masks patrol in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Police officers wearing protective masks patrol in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

A police officer wearing a protective mask stands guard at an old residential building in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

A police officer wearing a protective mask stands guard at an old residential building in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Coronavirus cases in Hong Kong’s Yau Tsim Mong district – a working-class neighborhood with old buildings and subdivided flats – made up about half of the infections in the past week.

A general view of old residential buildings are seen in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

A general view of old residential buildings are seen in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Sewage testing in the area picked up more concentrated traces of the COVID-19 virus, prompting concerns that poorly built plumbing systems and a lack of ventilation in subdivided units may present a possible path for the virus to spread.

Authorities said in a statement Saturday that an area comprising 16 buildings in Yau Tsim Mong will be locked down until all residents have undergone tests. Residents will not be allowed to leave their homes until they have received their test results to prevent cross-infection.

“Persons subject to compulsory testing are required to stay in their premises until all such persons identified in the area have undergone testing and the test results are mostly ascertained,” the government said in a statement.

Professor Yuen Kwok-yung, chair of infectious diseases in the University of Hong Kong's department of microbiology, second left, speaks to media in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Professor Yuen Kwok-yung, chair of infectious diseases in the University of Hong Kong's department of microbiology, second left, speaks to media in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Hong Kong has previously avoided lockdowns in the city during the pandemic, with leader Carrie Lam stating in July last year that authorities will avoid taking such “extreme measures” unless it had no other choice.

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

It appealed to employers to exercise discretion and avoid docking the salary of employees who have been affected by the restrictions and may not be able to go to work.

Government investigators wearing protective suits, walk in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Government investigators wearing protective suits, walk in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

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

Residents wearing face masks to protect against the spread of the coronavirus, queue at a temporary testing center for COVID-19, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Residents wearing face masks to protect against the spread of the coronavirus, queue at a temporary testing center for COVID-19, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Medical workers in a protective suits assist residents at a temporary testing center for COVID-19, in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Medical workers in a protective suits assist residents at a temporary testing center for COVID-19, in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Police officers wearing protective masks patrol in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

Police officers wearing protective masks patrol in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

A police officer wearing a protective mask stands guard at an old residential building in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)

A police officer wearing a protective mask stands guard at an old residential building in the Yau Ma Tei area, in Hong Kong, Friday, Jan. 22, 2021. Hong Kong's Yau Ma Tei area is expected to be put into lockdown due to the rising number of coronavirus cases. The territory has reported 9,797 positive cases and 166 deaths to date, according to Johns Hopkins University. (AP PhotoKin Cheung)