Police arrested Jamirul Islam, the grandfather of the two boys, on the day of the explosion. An eight-year-old boy, who was seriously injured in a bomb explosion at Ekdala village in Margram area of Birbhum district last Friday, succumbed to injuries on Wednesday at Burdwan Medical College and Hospital.
His cousin, also eight years old, who was injured in the explosion, is also admitted to the same hospital.
According to police, the two cousins had come to visit their uncle at Ekdala village last week and were playing in the house when they picked up a crude bomb stocked in the room.
Thinking it to be a ball, they started playing with the bomb. While they were playing, the bomb exploded, injuring the two cousins.
Both were taken to Rampurhat Medical College, but their condition deteriorated, and they were shifted to Burdwan Medical College.
Police arrested Jamirul Islam, the grandfather of the two boys, on the day of the explosion.