The blast, which injured 36 others, occurred yesterday at a roadside storehouse in Guangzhou city's Baiyun District when workers were unloading the caps containing gunpowder in small plastic rings. The production and transport of such materials is banned in China.
Police has detained three people, including a Jordanian man who owned the explosives, the state-run Xinhua news agency reported.
However, the Guangzhou Internet Information office said that the blast in southern China's commercial hub has been ruled accidental.
It was the second deadly blast to strike China in as many days. A huge explosion on Monday in front of a primary school in south China's Guangxi Zhuang Autonomous Region killed at least 2 persons and injured 44 others, including 26 students.