Shanghai will lock down the city in two phases to conduct a mass testing blitz for COVID-19, as authorities scramble to staunch a spiraling outbreak that’s challenging China’s zero-tolerance approach to the virus like never before.

At 5 a.m. on Monday, the city of 25 million people locked down areas east of the Huangpu River, which includes its financial district and industrial parks, for four days. The lockdown then shifts to the other half of the city, in the west, for another four days, according to a statement Sunday from the local government.

Residents will be barred from leaving their homes, while public transport and car-hailing services will be suspended. Private cars will not be allowed on the roads unless necessary. Production at Tesla Inc.’s Shanghai factory will be suspended because of the curbs, people familiar with the move told Bloomberg News.