Professor P Pramanik of IIT, Kharagpur, visited the blast site and collected samples. Besides this, two teams from the Forensic Science Laboratory (FSL) and Central Forensic Science Laboratory (CFSL) have already visited the spot to collect samples.

“We are clueless. Now we want to find out if there was any chemical reaction behind the explosion,” said Deputy Commissioner Vineet Kumar Goyal, Kolkata Police (headquarters).

“We have requested Professor Pramanik to conduct a separate probe into the matter. We have requested him to come up with the report as early as possible. We are waiting for his report,” he added.

Terming the explosion as ‘unprecedented’, Goyal said, “Initially we felt it could be due to electric wire explosion or explosion in the gas pipelines. But now these do not seem to be the reasons,” adding, “We are probing the matter in all possible ways.”