The Police say the suspect, a bus attendant had been working at the school for eight months.
Indians protest the rampant rape cases in the country
Angry parents scuffled with Indian police in riot gear at an international school near New Delhi Saturday after a staff member was arrested for slitting the throat of a seven-year-old boy during a sex assault.
Hundreds of parents on Friday stormed Ryan International School in Gurgaon after the body of Pradyuman Thakur was found in a school bathroom.
The Police said the boy was attacked with a knife after resisting a sex attack inside a lavatory. A bus attendant at the school has been arrested for the killing.
"The accused has confessed to the crime during questioning," Simardeep Singh, a deputy commissioner of police in Gurgaon, told AFP.
The boy resisted the sexual assault and the attacker decided to kill him to cover up the crime, Singh said.
The suspect had been working at the school for eight months, the officer said.
Parents of the nearly 1,000 students at the school tried to storm the campus on Saturday to demand the arrest of school managers over the case.
But hundreds of police in riot gear guarded the building to avoid a repeat of violence on Friday when chairs and cupboards were smashed.
The school has suspended the principal and assured cooperation with the investigators.
Authorities said they had launched an investigation into security at the school.
India's swelling middle class has fuelled the growth of private schools in the country that has a crumbling public education system.
But a lack of government regulation is a concern for parents.
Ranked one of the top educational institutions, Ryan international runs nearly 150 schools across India and in United Arab Emirates.
The school was caught in another controversy last year after a six-year-old student was found dead in a water tank at its New Delhi establishment.
Police arrested the principal, a teacher and three other staff for negligence in that case.