Suspect Chen Zhongshu, 54, was secretary of the land bureau in Panzhihua, a city of 1.2 million in the southwestern province of Sichuan, the official Xinhua news agency reported.
The attack occurred during a meeting of the municipal party committee and high-level city government cadres at the Panzhihua convention and exhibition centre, it said.
The gunman fired a series of shots, injuring city party chief Zhang Yan and mayor Li Jianqin before fleeing, Xinhua reported, without giving any details of motive or background to the incident.
The suspect killed himself after the attack and was found on the building's second floor, Xinhua said.
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Gun violence is rare in China, as private citizens are generally banned from owning firearms.
Chinese media outlet Jiemian.Com cited an unnamed city official saying Chen was known to have a stubborn personality and explosive temper.
During a land bureau meeting, it said, he once seized a colleague's phone after it rang and threw it down, smashing it into pieces.
Chen had complained in anger to friends that the party chief picked on him, Jiemian.Com reported.