There were no deaths but six police officers were injured, the reports said.
The violence erupted Sunday after four passengers of a car beat up a pedestrian following an accident in Chizhou, a town in Anhui province, the official Xinhua News Agency reported.
Police took the four passengers to the local station for questioning, but crowds surrounded the building, demanding that officers hand over the four people, Xinhua said.
The protest escalated, with thousands of people overturning cars and setting them on fire, smashing the windows of the station and looting a supermarket, the Web site Sina.com said.
The reports said thousands of people took part in the violence, but didn't give details about the number.
Rioters cut off power to the police building and threw firecrackers inside, the Web site said. Late in the evening, about 700 police finally succeeded in dispersing the 2,000 remaining protesters, the report said.
There was no information about the number of injured civilians.
Ten people were detained, while the four people involved in the beating of the pedestrian were still in custody, Xinhua said.