An explosion at a chemical factory in northern China has killed three and injured 37, state media reported Sunday, citing local authorities.

The blast occurred Saturday night in the city of Jinzhong, in northern Shanxi province, at the Yushe Chemical Co, the official news agency reported, citing a provincial government statement.

The cause of the explosion was still under investigation, the report said, adding that firefighters had worked into the early hours of Sunday to put out the fire caused by the blast.

The factory produced an array of chemicals ranging from common food additives to compounds used in making plastics and paper, according to the company website.

Two of the injured were in serious condition, the report said.

In China, considered one of the world's most dangerous places to work, an average of 187 people were killed in work-related accidents on each day in the first half of this year, the government has said.