Police in Anhui province detained 34 suspects for attacking police officers and government workers during investigations into pyramid selling.

The government workers were attacked at about 9 am on Saturday when they investigated a pyramid-selling case at a residential community in Hefei, capital of Anhui province, Hefei public security bureau said in a statement on Monday.

During the clash, the suspects - members of an alleged pyramid-selling group - summoned many others to the residential community and attacked police with bricks, according to the statement.

Twelve police officers and government workers were injured, with police catching five suspects at the scene, the statement said.

In the afternoon, members of the alleged pyramid scheme called in nearly 300 supporters who gathered near the residential community again, blocking the gate to the compound.

Police arrived and caught suspects who called for the people to attack the government workers, according to the statement.

Pyramid selling is illegal in China, and police will crack down on such activities, the statement added.

A photograph circulated on the Sina micro blog showed hundreds of people gathering on an eight-lane road near a plaza, with many people wearing dark clothes.

An online video showed that people who gathered at a road junction dispersed when several police cars arrived.

A video clip on Anhui TV showed stones and glass fragments scattered in the road, with blood on the ground.

"Lots of people surrounded the policemen. The police escaped, and the people chased and beat them," an elderly witness told local television.

Many police had head and eye injuries, the TV report said.

Phone calls by China Daily to Hefei public security bureau went unanswered on Monday.

A report by China Central Television showed a woman wearing a purple shirt stomping on a police officer's head after pulling him to the ground.

Police recently raided three pyramid-selling dens in Binhu, a new district of Hefei, CCTV reported.

It is not the first time police in Hefei have been attacked by pyramid-selling groups.

On June 16, suspects attacked officers and stole their guns at a residential community. Police detained more than 80 suspects, CCTV reported.

Ji Beibei in Hefei contributed to this story.