At least 12 workers died and 21 were injured when a boiler exploded at a factory in western Uttar Pradesh’s Hapur district of India on Saturday afternoon, officials said.

There were around 30 people in the affected area at the factory in the UPSIDC industrial area in Dholana, around 80 km from the national capital, when the incident occurred, they said.

The impact of the explosion was so intense that the roofs of some of the factories located in the vicinity were damaged. It took three hours for fire tenders to douse the blaze.

Superintendent of Police of Hapur Deepak Bhuker said 12 people had died and 21 were injured and undergoing treatment.

“The factory was given the licence to manufacture electronic items. And now, it is a matter of probe what exactly was going on here. This is a sad incident. Forensic teams have reached here and are collecting samples,” District Magistrate of Hapur Medha Roopam said.

“Our efforts are to ensure that the injured persons get the best medical treatment. Some of them have been referred to Safdarjung Hospital,” she added.

Other factories in the area will be inspected, the district magistrate said, adding that action would also be taken against officials concerned if it was found in the probe that the incident took place due to their laxity.

The factory is located adjacent to a CNG pump. Rescue and relief measures were taken up at the site, according to officials.