Police arrested a suspect, Shahin, 26, after a case was filed on Monday over the incident that took place on February 14.
The victim, a Class-VII student, was also admitted to Khulna Medical College Hospital in the evening.
Victim’s family members claimed that one Shariful Islam, 30, took some indecent photos of the girl several times when he used to live in the same rented house in Chandonimahal area of the upazila.
When the matter came to light, Shariful was driven out of the house.
On February 14, Shariful called the girl over mobile phone to meet him at Fulbari Gate, saying he would give back the photos.
When the girl went to meet him, he took her to his new house where he along with his two friends -- Shahin and Kajal -– violated her in turns throughout the night.
After returning home on February 15, the girl narrated the incident to her family members.
However, an influential group tried to hush up the matter.
As the girl fell sick on Monday noon, the family members along with the girl went the police station and filed the case.
Manjur Morshed, officer-in-charge of Dighalia Police Station, said they were investigating the incident.