The camp was held on the premises of the school and its organiser has also been arrested.
Krishnagiri district Superintendent of Police, P. Thangadurai while speaking to said that a girl was sexually assaulted and at least a dozen more were abused in a fake NCC camp at the school.
He said that the school authorities were aware of the sexual abuse but chose to suppress the matter instead of informing the police.
Police investigation said that the private school where the camp was held did not have an NCC unit. A group approached the school management and convinced them that holding a camp would qualify the school for an NCC unit.
The school agreed and police said that no background check was conducted before agreeing to the proposal.
The three-day camp was held in the first week of August and had 41 participants of which 17 were girls.
Police said that the girls were lured out of the auditorium where they were staying and were sexually abused.
The girls were accommodated on the first floor of the auditorium while the boys were on the ground floor and no teachers were in the auditorium to supervise the children.
The accused have been charged under the Protection of Children Against Sexual Offenses (POCSO) Act.
A senior official with the Krishnagiri District Child Welfare Committee told that the department has initiated action against the school authorities and the organisers of the camp.
The police are also probing if the group behind the fake NCC camp has conducted similar camps in other schools.