Five people were injured in an explosion in front of a multi-storey building in the Nagerbazar area in the citys northern suburbs on Tuesday, police said. The explosion was reported outside a fruit shop on the ground floor of the building in the congested Kazipara area under the jurisdiction of Dum Dum Police Station around 9 am, a police officer said. The injured have been rushed to the state-run R G Kar Medical College and Hospital, he said. The building also houses the office of South Dum Dum Municipality Chairman, the officer said. A forensic team and sniffer dogs have been sent to the spot to ascertain the nature of explosion, police said.