Tusshar (16) was found unconscious by some students in his school bathroom and was taken to a hospital yesterday. He was later referred to the GTB Hospital where he was declared brought dead.
CCTV footage revealed that he had a fight with some students near the washroom.
Three of the students with whom he had a fight have been apprehended, said a senior police officer, adding that they were minors.
One more student is on the run.
On the basis of a complaint by the boy's family, a case was registered.
A medical board will conduct post-mortem on the body later today.