A team from the Barrackpore police commissionerate on Saturday night raided a house in Halisahar town in North 24-Parganas and seized 3.5 quintals of banned firecrackers in the wake of the explosion in a firecracker unit in Kalyani on Friday.

The Friday blast had killed four women workers, turning the spotlight on illegal firecracker factories running in the area.

The team from the Barrackpore police commissionerate, led by the Bijpur assistant commissioner of police, carried out the raid in Sarkarpara, ward 3 of Halisahar town, acting swiftly to trace the manufacturing and stockpiling of banned firecrackers to prevent further blasts.

One person was arrested, while the owner of the house managed to escape.

"The banned firecrackers were stored under extremely risky conditions in the house of one Debu Khan. Acting on a tip-off, we conducted the raid and seized about 3.5 quintals of banned firecrackers. We arrested one Bidyut Halder, who had allegedly stored the items there. He was interrogated and later produced in a court in Barrackpore," a senior officer of the Barrackpore commissionerate said.

On Sunday, a CID team, accompanied by the bomb disposal squad, visited the Rathtala area in Kalyani where the illegal firecracker unit had exploded.

The team examined the remains at the blast site as part of an ongoing investigation. A state intelligence unit team also visited the site.

The CID team, with the support of its bomb disposal wing, later seized a large quantity of explosives and unfinished firecracker materials from the rooftop of the house of Khokon Biswas, the arrested owner of the illegal factory that had exploded.

Fire services personnel, who reached the site with bike-mounted portable water tanks, worked to neutralise the explosives by spraying water through hose pipes.

When the explosion occurred, fire tenders were unable to enter the location due to the narrow lanes. It forced the firefighting personnel to rely on manually splashing water from plastic buckets after getting them filled from a deep tube well.

The Nadia district administration has since begun identifying illegal firecracker units in Kalyani.

"According to our records, only two legally registered firecracker manufacturing units operate in the town with proper manufacturing licenses. Unless the other units are relocated to safer areas following the standard operating protocols of fire services and the Indian Explosives Act, they cannot be regularised with manufacturing licences," an official of the Nadia district administration said.