The death of a truck driver sparked violent protests overnight in Luzhou city in Sichuan province, Chinese reports say.
Local officials said a truck driver fell ill and died after scuffling with police. Protests broke out amid claims the driver had been beaten to death.
Photos circulating online showed large crowds of people, as well as cars being overturned and set on fire.
State media said calm had been restored by dawn on Thursday.
The official Global Times said in a report published on its accredited microblog that up to 10,000 people had taken part in the protests. The report was later removed.
A local resident told Reuters news agency several thousand people had taken to the streets.
‘Scuffled’
The local government said in a statement that Gan Junyuan, the driver, was told to move his truck by auxiliary traffic police officers in Longmatan district on Wednesday evening.
He “argued and scuffled” with the police, then “suddenly felt uncomfortable” during the scuffle, it said.
Mr Gan took some medicine but then his condition deteriorated, the statement said. Paramedics were unable to resucitate him at the scene and he died.
“I rushed to the scene… and saw that the victim, who was then surrounded by three traffic policemen, was suffering from some kind of heart attack, before asking someone to help him to get his drugs from his vehicle,” Hong Kong’s South China Morning Post quoted an eyewitness as saying.