The electronics giant’s vast plants in China churn out products for Apple and other tech firms, but it has been come under the spotlight after a series of suicides at its factories in the past two years.
Pictures posted online, the authenticity of which could not be confirmed, showed crowds of workers, a building with shattered windows, and an overturned police car, among other damage.
In a statement Foxconn’s Taiwanese parent company Hon Hai said the incident began “as a personal dispute between several employees” in a privately-managed dormitory for workers at the plant in Taiyuan, in Shanxi province.
It escalated to involve 2,000 workers and was brought under control by police after four hours, the company said, adding 40 people were injured.
But China’s state-run Xinhua news agency said a fight broke out between workers from two different Chinese provinces, “attracting more than 10,000 spectators and triggering chaos”.
Around 5,000 policemen were sent to the scene, it said, citing government officials, and they needed 10 hours to bring the situation under control.
Foxconn is the world’s largest maker of computer components and assembles products for Apple, Sony and Nokia, among others.
It employs about one million people in China, roughly half of them based in its main facility in Shenzhen, which borders Hong Kong.
The Taiyuan plant employs 79,000 workers and makes automobile electronic components, consumer electronic components and precision mouldings.
In 2010, at least 13 Foxconn employees in China died in apparent suicides, which activists blamed on tough working conditions, prompting calls for better treatment of staff.
“Foxconn is known to have a very authoritarian management style and discipline is very strict,” Geoffrey Crothall, spokesman of the Hong Kong-based China Labour Bulletin, told AFP.