Four people were killed on Friday in an explosion in a chemical factory in Bulandshahr district in Uttar Pradesh.
The incident took place in a house, where the factory was running, on Dhikoli road in the Nagar Kotwali area.
The house where the explosion took place has collapsed, more persons are suspected to be buried under the debris. Cylinder pieces have also been recovered from the spot.
The explosion was so strong that its sound was heard for two kilometres.
Senior officials have reached the spot and rescue work has begun.
Details are awaited.