The incident happened around 9:30 a.m. in Dazhou City, China's official Xinhua news agency reported.
Of those who died, two were dead at the scene, two died en route to a hospital and one died at a hospital after emergency treatment failed, the provincial administration of work safety said in a statement. Those injured were treated at local hospitals.
An investigation into the cause of the incident is under way.
Boston schools pull out free condoms over wrapping complaints
Millions of Getty images now available for free via embed tool