The blast ripped through adjacent shops and damaged the pedestrian walk, eye witnesses said.
"A large explosion took place outside a shop in Nagerbazar area today morning. What caused the explosion is yet to be ascertained. Several people have been injured in the blast," Barrackpore police Commissioner Rajesh Kumar Singh said.
"We are investigating the matter. The bomb squad of Criminal Investigation Department (CID) has been called to the spot. We have cordoned off the area," he said.
Trinamool Congress leader and Chairman of South Dumdum municipality Panchu Gopal Roy said the blast was targeted at him.
"I think they tried to target me. Today is October 2, the birthday of Mahatma Gandhi. We all know which group was involved in Gandhiji's killing. I will not be surprised if that same group was involved in this blast," he said.