Police said the blast not only ripped apart the tenement from where the unit was being run, but also seriously damaged to three neighbouring houses in the crowded Biwipur residential locality.
Police said, "Bodies of two men and a woman were recovered from the site of the blast, while another woman and a child's body was recovered from the debris of a neighbouring house later."
Cops do not rule out the possibility of at least three more bodies being trapped under the debris of other houses.
The blast that occurred at about 5.15 pm sent shock waves in and around the locality, that lies just behind the boundary wall of Kanpur based Hindustan Aeraunautics Ltd. factory that manufactures aircraft components for Indian Air Force.
The IAF aviation-testing zone is also at a stone's throw from the scene of the blast.
HAL security officer Major S K Rai told reporters in Kanpur, "Cracker manufacturers have been thriving in this locality that is being run from IAF encroached land; what surprises me that no effort has ever been made by the authorities concerned to check this menace."
(With PTI Inputs)