Police in Hampshire are investigating claims that at least two girls were sexually abused by other pupils at a mixed special educational needs boarding school.
Pupils at the Stanbridge Earls School in Romsey have been accused of forming a "predatory ring" that abused female students.
The investigation was launched after a special educational needs and disability tribunal found that the school had failed to protect two vulnerable girls from sexual abuse.
In January, the tribunal found that a 15-year-old autistic girl had been groomed for sex and raped by an older male student.
Police will be examining the tribunal's findings to establish if further offences took place.
Another 12-year-old girl was allegedly sexually assaulted in nearby woods on one occasion and stripped naked by five other students on another.
The girl who was 15 when she was allegedly attacked in 2011 was taken to the school doctor and an examination found that she had suffered vaginal injuries.
Staff members did not report the attack to her parents, the deputy head teacher or to the social services, the tribunal heard.
She was returned to school and continued to be taught alongside her male assailant. She was raped again the following month.
Her mother found out about the attack when her daughter told her weeks later.
During the hearing, it emerged that the school's head teacher, Peter Trythall, believed that non-consensual sex was not the same as rape and that when he was informed of the attack, he went on holiday to Cornwall. He later said his comments about rape were taken out of context.
Trythall also dismissed explicit text messages sent to the victim, saying it was normal for children to send these sorts of messages.
The tribunal said that the school was "unsystematic, unprofessional, ad hoc and completely inadequate" in protecting the girl.
After finding out that more students had alleged abuse at the school, the victim's parents said: "The fact that our daughter was not the only vulnerable underage girl subject to sexual contact and sexual intercourse was, and is, shocking to us.
"The secretary of state has the power to close this school. We would like him to exercise that power to enable the school to be rebuilt under a new management team. The behaviour was like something out of Lord of the Flies."
The parents were awarded £86,000 in costs from the school and were offered an apology.
A Hampshire Police spokesman said: "We are conducting a comprehensive review into previous allegations involving Stanbridge Earls School in Romsey.
"We are in contact with the families of the two girls who previously made allegations of abuse and are updating them with the progress of the review in respect of their individual allegations."
A statement from Stanbridge said: "The school has met the Department for Education and submitted a detailed action plan concerning how it is remedying the issues highlighted by the tribunal.
"It has engaged outside experts and acted swiftly and transparently at all times to ensure there can be no repeat of the circumstances that led to the tribunal."