A cluster of explosive-manufacturing units in Waidhan, the headquarters of Singrauli district, was rocked by a blast on Sunday evening that left at least nine workers dead and more than 40 injured.

More than 20 licensed units in the industrial area manufacture explosives used for blasting in coal mines. A high intensity blast took place in Ideal Explosive Factory in the evening that also reduced to rubble REPL, the neighbouring unit. Other units in the area are also believed to have suffered heavy damages.

The intensity of the blast was so high that even those outside the unit were affected by it. The blast was followed by a power failure and a cloud of smoke covered the area, isolated from the residential localities. SP Anurag said rescue operations were on because some people could still be trapped inside the rubble. “It’s difficult to give any number,” he said, adding that at least six of the injured were critical.

Collector P Narhari told The Indian Express that eight bodies had been recovered while 35 people were admitted to the district hospital. He said between 50 and 55 people were working in the two units when the incident took place. The police control room said nine bodies had been recovered by midnight.

The units can’t keep any ignitable material. It was unclear what caused the blast. Narhari said experts from Satna had been called to probe the blast.