A meat cleaver-wielding attacker killed two people and injured nine others during a rampage at a Walmart in Southern China on Sunday night.
A 30-year-old unemployed man was detained as a suspect, Shenzhen police said. A motive for the attack was not immediately known, and no nexus to terrorism was announced.
Firearms are largely unobtainable in China for the ordinary citizen so many attacks are carried out using knives and homemade explosives, which has prompted stricter regulations in knife sales.
Perpetrators of most past attacks have been described as being mentally ill or bearing grudges against society, with social dislocation and a lack of resources for diagnosing and treating such conditions contributing to the problem, experts say.
The Associated Press contributed to this report.