Chinese police say they have detained 25 people after clashes between rampaging migrant workers and security forces near the southern city of Guangzhou.
The rioting late on June 12 followed three days of protests in the town of Xintang triggered by the alleged mistreatment of a pregnant street vendor by security wardens.
The official Xinhua news agency said protesters hurled bottles and bricks at government officials and police vehicles, causing the police to use tear gas to disperse them.
Witnesses say a number of police vehicles were set on fire.
Police later seized control of the area in southern China's manufacturing heartland, which is home to textile factories employing many migrants.
Violent protests driven by resentments over social inequality, abuse of power, corruption, or poor wages have become frequent in China over the past decade.
Last week, hundreds of people laid siege to local government offices in the city of Lichuan, in the central province of Hubei, after the death of a local official while in police custody.
The family of the official, Ran Jinxian, said he was beaten to death during interrogation.
Residents say Ran was arrested because he refused to cooperate with his superiors in a campaign of land requisitions.
Several officials have reportedly been detained or are under investigation over Ran's death.
In May, an ethnic Mongolian animal herder was crushed under a coal truck, triggering street protests over mining practices in the northern province of Inner Mongolia.
And a man apparently angry over corruption by local officials and land seizures set off three homemade bombs at government buildings in the southern province of Jiangxi, killing himself and at least two other people.
The Chinese leadership has reacted nervously to recent uprisings sweeping the Middle East and North Africa. Rights groups say hundreds of government critics have been subjected to repressive measures in recent months, including police summonses, detentions, and house arrests.
compiled from agency reports