China began its largest coronavirus lockdown in two years, as millions of people in the financial hub of Shanghai are to be confined to their homes starting Monday to curb an ongoing outbreak of COVID-19, writes DW.

Shanghai, China’s largest city with 26 million people, had previously managed smaller outbreaks with limited lockdowns of housing compounds and workplaces. The citywide lockdown will be China’s most-extensive since the virus first broke out in Wuhan.

SARS-CoV-2 was first detected in the central city in late 2019, which led to the confinement of its 11 million people for 76 days in early 2020.

Authorities said the two-phase lockdown of Shanghai will be used to carry out mass testing.

In the first phase, the sprawling eastern district known as Pudong has been placed under confinement. The area will remain under lockdown till Friday, after which the more-populated western Puxi section will be placed under lockdown.

They city has seen regular spikes of COVID-19 infections, with another record high of 3,500 cases reported on Monday.