Six labourers were killed and six others severely injured in an explosion at a petro-chemical factory in Uttar Pradesh’s Bijnor on Wednesday, reported the Hindustan Times. At least three labourers are reportedly missing.

According to the police, the blast took place around 8 am when a boiler at Mohit Petro-Chemical Factory was being repaired. “As per information gathered so far, the boiler of the factory was not functioning for the past few days,” Superintendent of Police Umesh Kumar Singh told PTI. “Today, while it was being repaired, there was a blast in the boiler while welding work was going on.”

Singh said six men – Kamalveer, Lokendra, Ravi, Chetram, Vikrant and Bal Govind – died on the spot, while six others are in the district hospital in a critical condition. Three people have been missing since the explosion.

Singh said efforts are on to trace the owner of the factory. Bijnor district collector and superintendent of police are present at the site, reported The Indian Express.