More than 200 migrant workers gathered Monday night at a government building in south China's Guangdong Province, protesting over a wage-related dispute that led to injury, Xinhua reported.
The crowd in front of the township government building of Guxiang, Chaozhou City, was dispersed by police at about 10:30 pm.
According to the local authority, at least three cars were smashed and another one burnt.
Nine people allegedly involved in the violence had been arrested, local police said early Tuesday.
The protest was led by a migrant worker surnamed Xiong who works for a local ceramics workshop.
Xiong was wounded in a knife attack after he argued with his boss for the delay of his wage at the workshop last Wednesday, police said. Three people had been arrested for the knife attack.
The case is still under investigation.