The official Xinhua News Agency said Sunday that the death toll rose from the original 16 killed in Tuesday’s blast. About 100 people were working at the Hebei Zhaoxian Keeper Chemical Co. plant in Hebei province’s Zhaoxian county.

Xinhua earlier said rescue work was dangerous because of the risk of other explosions.

China’s State Administration of Work Safety said the blast occurred during production of a high-energy fuel and propellant, guanidine nitrate.