According to police, the shed caught fire accidentally when the boys were lighting cigarettes.
While three boys charred to death, one managed to escape and saved his life.
The incident occurred on Friday morning under Sepon police station.
Two of the deceased have been identified as Bivan Munda and Anud Munda of the same family.
Police said that the incident was reported around 10:30 am on Friday. Four minors were playing at the thatched shed. They were lighting cigarettes inside the shed when it caught fire. One managed to escape, the other three were burned to death.
The police team from Sepon police station have reached the spot and started investigation.