Hong Kong television showed seething crowds of migrant workers from the southwestern province of Sichuan running through the streets of Zengcheng, smashing windows, setting fire to government buildings and overturning police vehicles.
Riot police were shown firing tear gas on Sunday night, deploying armored vehicles to disperse the crowds and handcuffing protesters.
Witnesses said there were more than 1,000 protesters and at least one government office had been besieged.
Thousands of riots, protests and other forms of unrest break out across China each year over problems ranging from rampant inflation to corruption, a big wealth gap, industrial pollution, forced demolitions and abuse of power.
The Chinese Communist Party maintains strict political and media controls to quash any form of organized dissent.