Three people were missing and four injured in an explosion at a biotechnology company facility in Xiangcheng city, Henan province, on Thursday, local authorities said.
The flames at the scene were extinguished after the blast occurred at 11:09 am, and the injured were sent to hospital as rescue efforts continued, according to the local government announcement on its official website.
The cause of the explosion remains unknown, and experts have been dispatched to the scene to carry out technical investigations, it added.
Liu Boqian contributed to this story.
