A seven-year-old child was killed and nine people, including his mother, were injured in a low-intensity explosion in front of a multi-storey building at Nagerbazar in Kolkata's northern suburbs on Tuesday, police said.

The ruling Trinamool Congress (TMC) held the BJP responsible for the blast and alleged that the saffron party was aiming to kill South Dum Dum Municipality Chairman and TMC leader Panchu Roy. But the BJP rubbished the charges.