SHANGHAI, (Reuters) –U.S. automobilemaker Tesla (NASDAQ) has suspended production at its Shanghai plant for four days. This is after two sources familiar with the matter revealed that the city had announced Sunday night that it would close down two levels to conduct mass testing for COVID 19.

According to people, the company informed its suppliers and workers about the change.

According to one source, it attempted initially to make a closed loop in order to keep production going and called workers back on Sunday. According to the source, after realizing it had not enough food for them, they were allowed to depart that night.

Tesla did not respond immediately to Monday’s request for comment.

China’s financial center of Shanghai announced Sunday that it will lock the city down in two stages for COVID-19 testing, which is expected to take place over nine days.

According to authorities, they will divide Shanghai into two using the Huangpu River which flows through it as a guide.

The Tesla factory can be found in Pudong New Area’s Lingang District. It is part Shanghai’s initial lockdown stage. The lockdown began Monday morning and will continue until Friday morning.