A teenager playing cricket in Patuli was injured while fiddling with a suspected crude bomb that he mistook for a ball on Friday morning.
Firecrackers had been burst on the same ground on Thursday night.
Police said Dhoni Sarkar, 15, suffered injuries in his ears, face and nose.
He was first taken to Baghajatin State General Hospital and from there to MR Bangur Hospital for treatment.
The police suspect that the unexploded crude bomb could have been used during Diwali as a cracker.
An eyewitness said Dhoni and his friend Sayan Dhali were playing cricket around 11.30am when the explosion occurred.
“Sayan was batting and Dhoni was bowling. Sayan hit the ball and Dhoni ran to fetch it. But he stumbled on something white and mistook it for the ball. He was fiddling with it when it exploded,” said a neighbour who went to ground around the same time.
The spot where Dhoni was injured is close to Patuli police station.
A team of officers from the station rushed to the spot and took him to the hospital.
Another eyewitness said the explosion caused a lot of smoke which covered that portion of the playground.
“There was a loud bang and the ground was filled with white smoke. When I went close to the spot, I saw two children running away. One of them was injured. They ran to a tap. The injured boy was splashing water on his face,” said the resident.
The police said they were scanning CCTV cameras in the area to see if any suspicious movement was spotted on Thursday night or Friday morning.
People in the locality said firecrackers had exploded on the same ground till late on Thursday night.
The police said a forensic team would visit the spot and examine the remains of the bomb that exploded to ascertain the nature of the explosive.
Till Friday evening, the source of the bomb could not be identified.