As many as 10,000 Chinese rioted in southwest Sichuan province Wednesday after residents said a truck driver was beaten to death by police during a routine traffic stop.
The official Xinhua news agency says calm has been restored in the city of Luzhou as of early Thursday. Although no casualties were reported, it says seven police cars were burned during the unrest.
Online reports say police used tear gas to disperse the protesters, who attacked police with rocks and bottles.
State media quickly denied reports that the man, identified as Luzhou resident Gan Junyuan, was beaten by police. The Communist Party-controlled
Global Times quoted officials who said he died of an "acute disease" after being told to move his illegally parked vehicle. Xinhua said Gan "suddenly felt uncomfortable" and died while scuffling with police. It said doctors who were called to the scene were not able to save his life.
Pictures and video circulated on
Chinese social media, which could not be independently verified, show a body lying motionless next to a truck as police held back protesters.
The local government has promised to conduct an investigation.
Tens of thousands of riots break out across China every year in response to police brutality, land grabs, factory pollution and other grievances. So far, the protests have been localized and have not posed a serious threat to the rule of China's Communist Party.
The party is working hard to enforce calm ahead of a sensitive once-a-decade leadership transition that begins next month with its 18th Party Congress in Beijing.