Officer Li Qi is in critical condition while the others are in stable condition, said doctors with the No.1 People's Hospital of Jiujiang City.

The journalist is from the Xunyang Evening News. The three other who were injured are officials with the administrative bureau for industry and commerce of Jiujiang City.

The city's public security office says it has detained more than 40 people who are accused of attacking the investigators.

The victims were investigating a pyramid selling scheme in a residential neighborhood located in the city's Lianhua Street. About 100 member involved in the scheme attacked the investigators with iron bars as police were taking away the alleged organizer of the scheme.

More than 100 policemen were called in to restore order, according to the public security office, which provided no further details.

Pyramid selling, which has cheated thousands of innocent investors, was banned in China in 1998.