The school failed to conduct background checks on the group that they had engaged for the camp.
A girl was sexually assaulted and at least a dozen others were sexually abused at what turned out to be a fake National Cadet Corps (NCC) camp in Tamil Nadu's Krishnagiri, police said on Monday.
Eleven people, including the organiser of the so-called camp, the school's principal, two teachers and a correspondent have been arrested.
Investigations revealed that the private school had no NCC unit and a group approached the school management with the claim that hosting such a camp would qualify them for one, police said.
The school failed to conduct background checks before hiring the group for the camp.
As many as 41 students, including 17 girls, participated in the three-day camp held earlier this month.
The girls were accommodated in the school auditorium on the first floor, while the boys were housed on the ground floor. No teachers were assigned to supervise the camp. The girls alleged that they were lured out of the auditorium and sexually assaulted.
"The school authorities were aware of the sexual offences but chose to suppress the matter instead of informing the police. The students were allegedly instructed to not take it seriously," District Superintendent of Police, P Thangadurai told NDTV.
The police are also probing if the group behind the fake NCC camp has conducted similar camps in other schools.
The accused have been charged under the stringent Protection Of Children against Sexual Offences (POCSO) Act.
Medical examinations of the girls have been conducted and the District Child Welfare Committee has initiated action.
The case comes amid nationwide outrage over the horrific rape and murder of the 31-year-old trainee doctor at Kolkata's RG Kar Hospital.