Nine of the injured have been released after preliminary medical assistance at Baruipur hospital. The condition of one among the remaining four, who were referred to a state-run hospital in the city, is stated to be critical, he said.
The incident occurred at Sonarpur's Gobindopur area.
Three fire tenders were pressed into service to douse the flames which broke out at the factory at around 12.40 pm on Sunday, a fire department official said.
"This was a small factory with only a tin shed and small walls on four sides. There were some finished and unfinished firecrackers at the factory," the official said.
The fire was doused at around 3.40 pm, he said.
"The owner is undergoing treatment in the hospital and we are waiting for his release to question him," the police officer said.
Other materials and commodities used to manufacture firecrackers were seized from the factory, the officer added.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)