Two farmers and two police officers were killed in China's northern Habei province on Tuesday.
State television CCTV reported the incident as a "mass shooting" and said five people were also wounded.
According to local media, a 55-year-old man with bipolar disorder was the main suspect and was killed during the shooting.
The incident occurred in a village and officials said they are investigating the possible reasons behind what happened.
Mass shootings are rare in China, where access to guns is strictly controlled.
In December an employee of China's central bank shot and killed two colleagues at the branch he was working at in the northeastern province of Liaoning.