The trigger for the protests, which began early on Wednesday, appeared to be a plan to delay bonus payments, many of the demonstrators said on livestream feeds. The videos could not be immediately verified by Reuters.

"Give us our pay!", chanted workers surrounded by people in full hazmat suits, some carrying batons, according to footage from one video. Other footage showed tear gas being deployed and workers taking down quarantine barriers. Some workers had complained they were forced to share dormitories with colleagues who had tested positive for COVID-19.

Foxconn, formally called Hon Hai Precision Industry Co Ltd, said in a statement it had fulfilled its payment contracts and that reports of infected staff living on campus with new recruits were "untrue."

"Regarding any violence, the company will continue to communicate with employees and the government to prevent similar incidents from happening again," the company added.

As for what drives these protests, one person said "Foxconn never treats humans as humans."

A source familiar with the situation in Zhengzhou said production at the plant was unaffected by the worker unrest and output remained "normal."

Discontent over strict quarantine rules, the company's inability to stamp out outbreaks and poor conditions including shortages of food had caused workers to flee the factory campus since the Apple Inc. supplier imposed a so-called closed loop system at the world's biggest iPhone plant in late October.

Under closed-loop operations, staff live and work on site, isolated from the wider world.

The rare scenes of open dissent in China mark an escalation of unrest at the massive factory in Zhengzhou city that has come to symbolize a dangerous build-up in frustration with the country's ultra-severe COVID rules as well as inept handling of the situation by the world's largest contract manufacturer.

Reuters earlier reported that iPhone output at factory could slump by as much as 30% in November, and that Foxconn aimed to resume full production there by the second half of the month. Apple Inc. had warned it expects lower shipments of premium iPhone 14 models than previously anticipated.

While the latest unrest has added "uncertainties" to the target, the source said the company was still working hard to reach it, adding that "only a portion" of the new recruits took part in the unrest.

A second source familiar with the matter, however, said Foxconn was unlikely to hit the target, pointing to disruptions caused by the unrest, impacting particularly new recruits who were hired to bridge the gap in the workforce.

The disruptions may shift some iPhone sales into the March quarter from the key holiday quarter, D.A. Davidson analyst Thomas Forte said.

Foxconn accounts for 70% of iPhone shipments globally. It makes most of the phones at the Zhengzhou plant, though it has other smaller production sites in India and southern China.

Apple did not respond to requests for comment.