“Due to our diversified production sites in China, we have adjusted the production line to minimize the potential impact,” Foxconn said in a statement.

Shenzhen, a tech hub near Hong Kong, was put under lockdown earlier Sunday following a surge of new COVID cases. While Foxconn did not specify how long the campuses will be shut, it said in its statement that they will remain closed until they have the green light from local government. The city lockdown is set to last until at least March 20.

While most of Foxconn’s iPhone production in China is done at its plant in Zhengzhou, in central China, the Shenzhen campuses — technically in the suburbs of Longhua and Guanlan — are its largest, with an estimated 450,000 employees. Foxconn has about a dozen facilities across China.

A number of other Shenzhen-based tech companies will be affected by the lockdown, including Huawei and Unimicron
3037,
-4.46%
— another supplier of Apple, as well as Intel Corp.
INTC,
-1.78%
and Nvidia Corp.
NVDA,
-2.46%
— according to a report by Nikkei Asia.

Foxconn shares were down about 1% in Taiwan trading as of late Sunday.