A local official of Panzhihua named Chen Zhongshu shot Party head Zhang Yan and Mayor Li Jianqin at the Panzhihua Convention Center. He eventually shot himself in the head.
Chen is the director of the city's land and resources bureau.
The motive behind the attack remains unknown but speculations on graft-related issues might be at play.
According to news portal jiemian.com, sources close to the suspect said that Chen had been complaining about the Party chief and how Zhang had made things difficult for him.
In May 2013, Chen became director of the land and resources bureau of Panzhihua. He was then awarded for his good work performance in Sept. 2015.
A Communist Party circular praised Chen for "leading the city's land and resources management to a path of more legalized and standard development."
Other reports revealed that Li was investigating Chen before the shooting.
Panzhihua, located in the mountainous area of southwest Sichuan, is a center for iron ore, vanadium and titanium mining. Chen has been in charge of land management for the past two years.
The Communist Party sees the shooting as related to the downfall of cliques of corruption in their organization.
China's Communist Party cadres were warned on Tuesday to learn from the downfall of the faction of corrupt officials, known as the "Petroleum" and "Secretary" gangs.
In an article published by the Party's anti-graft watchdog, a warning was stated as, "[We] must constantly be alert of, discover and punish in time those who form their own circles within the Party.
"The Petroleum Gang and the Secretary Gang have already been eradicated. They are lessons to be learned and others should watch their steps. If you don't toe the line, get out," read the piece in the "China Discipline Inspection Paper."