Six million people were on Friday under Covid lockdown in a Chinese city home to the world's largest iPhone factory, after clashes between police and workers furious over pay.
Authorities have ordered residents of eight districts in Zhengzhou, in the central province of Henan, not to leave the area for the next five days, building barriers around "high-risk" apartment buildings and setting up checkpoints to restrict travel.
There have been only a handful of coronavirus cases in the city.
The orders follow protests by hundreds of employees over conditions and pay at Foxconn's vast iPhone factory on the outskirts of the city, with fresh images of rallies emerging Friday.
Video footage published on social media and geolocated by AFP showed a large group of people walking down a street in the east of the city, some holding signs.
"So many people," a man can be heard saying. AFP was unable to verify precisely when the protests took place.
And after scores of workers left the plant Thursday with payouts of 10,000 yuan ($1,400) from Foxconn, posts on Chinese short-video apps Douyin and Kuaishou said the Taiwanese tech giant was turning away many of the thousands of people that had answered its hiring ads after a raft of departures in October.
Many of those who have arrived to take up newly vacant posts at the factory are now stuck in quarantine hotels outside the plant, multiple workers told AFP.
"We are in a quarantine hotel, and have no way of going to the Foxconn campus," one worker who asked to remain anonymous said.
Another employee said those turned away had been promised 10,000 yuan in compensation for being forced to quarantine, but received only a fraction of that amount.
"They are not letting us start the job and we cannot return home, Zhengzhou is under lockdown," one worker forced to quarantine in nearby Ruzhou city, after being promised employment at Foxconn, told AFP.
He added that there were multiple small-scale protests in other Henan cities by Foxconn workers made to quarantine and unable to start work.
The unrest in Zhengzhou comes against the backdrop of mounting public frustration over the government's zero-tolerance approach to Covid, which compels local authorities to impose gruelling lockdowns, travel restrictions and mass testing.
With China's daily caseload at 33,000 on Friday -- a record for the country of 1.4 billion -- the unrelenting zero-Covid push has sparked sporadic protests and hit productivity in the world's second-largest economy.
In the southeastern manufacturing hub of Guangzhou, millions of people have been ordered not to leave their homes without a negative virus test.
Social media footage published on Friday and geolocated by AFP showed residents of the city's Haizhu district dismantling barricades and throwing objects at police in hazmat attire.
"What are you doing? What are you doing?" one police officer holding a shield can be heard asking as he and his colleagues back away from the projectiles.