Three women of the same family, including a minor were killed and several persons were injured in a blast at an illegal firecracker manufacturing unit at Budge Budge, about 26km from the city.
The blast took place on Sunday evening at around 8.30pm and the three killed are 65-year-old Jamuna Das, her daughter Pampa Ghati and her 10-year-old granddaughter Jayashree, the police of South 24-Parganas, under which the area falls, said the police on Monday.
The incident was the second of its kind in West Bengal in a week.
At least 30 people, allegedly running illegal firecracker manufacturing units in the locality, were arrested and a large quantity of explosives stored in different houses were seized during police raids throughout the intervening night of Sunday and Monday, the police official said.
The number of injured was, however, not specified.
The three were on the terrace of the single storied house where the incident took place.
"Three women, including a minor, were declared brought dead when they were taken to a nearby ESI hospital. All of them had suffered third-degree burn injuries from a blaze which was reported from the terrace of their house, where an illegal firecracker factory was operated," a senior police officer of Diamond Harbour Police District told PTI.
"We have conducted raids in the area and seized at least 20,000kg of explosive materials used to manufacture firecrackers and arrested more than 30 people for their involvement in running such illegal businesses. Raids are on and police are investigating the cause of the fire," the officer said.
On May 16 an explosion had taken place at an illegal firecracker manufacturing unit at Egra in Purba Medinipur district in which 12 people lost their lives.
The main accused in the Egra blast died at a hospital at Cuttack in Odisha on May 19.
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