An eight-year-old student died in Murshidabad's Daultabad area when what he thought was a toy exploded late on Thursday afternoon.
Muklesur Rahaman of Chaudanga village was a Class II student of Chaudanga Primary School.
Local sources said that after returning home from school, the boy found a metal object lying by a pond nearby. Mistaking it for a toy he picked it up.
The metal piece turned out to be an explosive socket bomb. The explosion occurred when the boy accidentally triggered it by throwing it against a wall. It exploded instantly with a loud and killed Muklesur.
Local residents, alarmed by the sound of the explosion, rushed to the spot and found the body of the boy in fragments owing to the explosion.
Asim Khan, the ASP of Lalbagh, said a probe was on to find out who had left behind the bomb.
No arrests have been made yet, the police said.
After the state panchayat elections, a series of bomb blasts occurred in Murshidabad district, with many losing their lives and many more suffering severe injuries.
In September, another child lost his life in the Salar area while playing with a bomb. Two deaths occurred in October in Hariharpara area.
In November, three children were severely injured in Farakka while playing with a bomb.