Chinese authorities on Wednesday locked down the area around the world’s largest iPhone factory after workers fled the plant to avoid a virus outbreak and the resulting restrictions.

All people except Covid prevention volunteers and essential workers “are not allowed to leave their homes except to receive Covid tests and emergency medical treatment,” officials at the economic zone of central China’s Zhengzhou Airport said on Wednesday.

The move comes after pictures surfaced on Chinese social media last week showing people escaping from the facility, which is run by Taiwanese tech giant Foxconn and employs hundreds of thousands of workers.

Employees complained online about poor conditions and were forced to flee the factory on foot to avoid Covid transport restrictions.

China is the latest major economy to commit to a zero-Covid strategy, sticking to quick lockdowns, mass testing and lengthy quarantines to contain emerging outbreaks.

But new variants have tested local officials’ ability to wipe out flare-ups faster than they can spread, leaving much of the country living under an ever-changing mosaic of Covid curbs.

The district in the city of Zhengzhou said on Wednesday that all companies would have to work from home, with only “key companies” in the district allowed to continue working, without specifying which companies fall under that category.

Only medical vehicles and those delivering essentials are allowed on the roads.

The district’s more than 600,000 residents must undergo nucleic acid tests every day, the local government said, warning that it would “take firm action against all types of violations”.

Foxconn said over the weekend it was testing employees daily and keeping them in a “closed loop” as well as offering transportation to those who wanted to leave, after videos on social media showed employees walking down freeways with their suitcases.

Local governments around the city of Zhengzhou have urged Foxconn workers to register with authorities when they return home and complete a multi-day quarantine upon arrival.

The company added on Tuesday that it would quadruple bonuses for employees willing to stay at the factory during the outbreak.

China on Wednesday reported more than 2,000 fresh domestic infections for the third straight day.

Henan Province, where Zhengzhou is located, officially reported 359 Covid-19 infections on Wednesday, a jump from 104 on Tuesday.

South China’s manufacturing hub of Guangzhou this week also announced partial lockdowns in several districts in response to rising case numbers.