A pre-dawn blast at a dye factory in central China on Thursday sparked a fire that spread to employee dormitories, killing at least four people and injuring 108, the local government said.
A tank of chemicals used for dyes exploded at the Luo Dye Company Ltd factory in Yanshi city in the central province of Henan, the city's propaganda department said in a statement.
Firefighters put out the blaze five hours after it began. Four people died and 108 people were hospitalized, including seven with life-threatening injuries, the report said.
Rescuers were still searching for three people missing amid the burnt rubble this afternoon, state-run CCTV said.
The broadcaster did not say how much damage was caused or why the explosion happened but said a formal investigation had been launched.
A spokesman surnamed Ji at the Yanshi propaganda department declined to give further details.
Workplace accidents are common in China, where thousands die every year in part because of lax enforcement of safety rules and poor worker training.