The police said that a short-circuit caused the fire yesterday in the one-room hostel where 74 students stayed.
Local residents rescued all the students except the girl Emjouly Malsum who died on the spot.
The injured were sheltered in a government building and the government and Red Cross society of Dharmanagar Bloc were taking care of them.
Assistant Director of School Education of North Tripura district Barun Das said that a Christian missionary group had obtained permission to run a primary school, but admitted students up to class nine.
It had no permission either to run the hostel.
The police is investigating the matter.