State media say an explosion at a chemical factory in eastern China has injured two people and left nine others missing.

The Xinhua News Agency said the cause of the explosion Wednesday at a workshop owned by Tianbao Chemical Industry Co. in Shandong province is still unknown. The company manufactures explosives for mining and other commercial uses.

Xinhua said one of the injured is in critical condition.

The explosion is the latest in a string of serious accidents involving deadly chemicals in China. In August, 173 people, many of them firefighters, were killed in a chemical explosion in the port of Tianjin involving 700 tons of highly toxic sodium cyanide.