A Class 10 girl was gang-raped allegedly by fellow students at a boarding school in Sahaspur in Dehradun district and the matter was kept under wraps by the school authorities for over two weeks, according to the police.Nine persons — four students accused of perpetrating the crime and five members of the school staff, including its director, principal and administrative officer — have been arrested, Additional Director General of Police (Law and Order) Ashok Kumar said on Tuesday.The matter came to light on Monday, over a month after it took place on August 14, he said. The survivor first confided her ordeal to her elder sister when she realised that she might be pregnant.Threat to throw victim, sister out of schoolHer elder sister, who studies in the same school, drew the attention of the school authorities to the incident but instead of reporting the matter to the police, they tried to hush it up, Mr. Kumar said. They threatened to throw the two girls out of the school if they disclosed it to anyone. The school authorities are even accused of trying to abort her pregnancy, the police officer added.However, the elder sister later shared ithe information with a relative who informed the police about it. The arrested school staff are its director Lata Gupta, Principal Jitendra Sharma, administrative officer Deepak Malhotra, his wife Tanu Malhotra, and a maid named Manju.Police said that on August 14, the victim was taken to the backyard of the hostel by a classmate on the pretext that a teacher was calling her. When she reached there she found another classmate and two seniors waiting for her. They forcibly took her behind the bushes and raped her, the police said.