The explosion took place this morning in Mahlakpur village in Civil Lines area when Azim (14), Shannu (7) and Rihan (5) were playing near a garbage bin, police said.
Police suspect there were more than one explosives of crude nature placed on the garbage bin.
As of now the exact number of bombs is not known, said IG (Law and Order) Satish Ganesh.
A probe has been initiated, he said.
The condition of the three children was stated to be stable.