The deceased has been identified as 24-year-old Amit Khurana who was found in a pool of blood on the ground floor of the Guru Hariskishan Public School, police said.
Police took him to a nearby hospital where doctors declared him brought dead.
Police have not recovered any suicide from him. Khurana lived close to the school and had reached the spot without informing his mother, they added.
His relatives told the police that he was depressed over something for the last couple of months which might have triggered this extreme step, police said.