Five people were killed and four injured on Monday by noxious gas poisoning at a biochemical company in Zhangjiakou, North China's Hebei province, according to an official Weibo account of the local government in Huailai county.
The incident occurred around 16:30 on Monday at the Great Wall Biochemical Engineering Co Ltd in Huailai when the company was cleaning a sewage sedimentation tank.
The injured have been sent to a local hospital and they are in stable condition.
An investigation is underway for the cause of the incident.
