The blast occurred at 6:30 pm (1030 GMT) Thursday at an industrial park in Sichuan province's Yibin city, according to a statement on the website of the local work safety administration.
Photos on a local news website showed what appeared to be the burned out shell of a building surrounded by rubble.
The building was owned by chemical manufacturer Hengda, which was "conducting illegal construction at the plant which had not passed safety and fire control checks", the official Xinhua news agency said late yesterday, citing local authorities.
The Ministry of Emergency Management has sent a team to further investigate the cause of the explosion, the agency added.
In 2015, giant chemical blasts in a container storage facility killed at least 165 people in the northern port city of Tianjin. The explosions caused more than USD 1 billion in damage and sparked widespread anger at a perceived lack of transparency over the accident's causes and its environmental impact.
A government inquiry eventually recommended 123 people be punished. Tianjin's mayor at the time of the accident was sentenced to 12 years in prison for graft in September.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)