According to the police, Katib, son of Sizauddin, went to school on Wednesday morning but the family was told that he had died.
"We rushed to Guru Teg Bahadur Hospital in Delhi where doctors said the student was brought dead and the body had been sent for autopsy. In the evening, we performed the last rites," Mr Sizauddin said.
Katib was a student of J D Shastri Public School at Loni in Ghaziabad, the family said.
Afsana, the boy's mother, said: "My son had been complaining about his teacher ... He said he was being harassed in the school but we ignored it."
School Manager Mahesh Kumar Sharma told the family that the student was initially taken to Dharampal Memorial Hospital in Loni and then to Delhi.
Mr Sizauddin said the entire sequence of events raises several questions.
"What happened to the boy after reaching the school? Why was he rushed to the Loni hospital and then to GTB Hospital? What happened in between? Why we were not intimated about the condition of the child earlier?"
Assistant Superintendent of Police Anoop Singh said: "We are awaiting the autopsy report. We will initiate legal action accordingly."