With a 12-year-old boy succumbing to injuries at the Government General hospital on Tuesday night, the toll in the blast in Puducherry on Saturday rose to two.
Two other boys injured in the blast were recovering at the hospital, the police said.
The incident occurred when the boys from Vanarapet, while playing found a packet containing the bomb near the railway track. When Ajit Kumar (12) opened the packet the bomb exploded, killing him on the spot and injuring three others.
The police registered a case and investigation was on.
A few people picked up in connection with the hurling of a bomb at the house of one Ganesh of the same area were being interrogated to establish if there was any link with the hurling of the bomb and the blast.