Anilkumar, a passenger from Thiruvananthapuram, proceeding to Ramagundam had lodged a complaint that some persons had hurled stones at the train last night, resulting in a serious head injury to his son Aromal.
The family got down at Tirupur and the boy was given first aid at a private hospital, railway police said.
Based on the complaint, police took the five teenagers into custody today for questioning, they said.