All the four accused, including two minors, were detained last night, they said.
The girl had abruptly discontinued going to school prior to the alleged offence and used to be at home in Palghar town. A 22-year-old youth raped her several times during the past eight months at her place when the girl's mother used to go out for work, assistant police inspector D R Salunkhe said.
During the same period, another youth from the locality also raped her a couple of times, he said.
The girl had recently gone for a medical check-up when it came to light that she was 16 weeks pregnant, he said.
Subsequently, her parents lodged a complaint last evening following which the youths were detained, he said.
A case under IPC sections 376 (rape), 376(d) (gangrape) and relevant provisions of Protection of Children from Sexual Offences (POCSO) Act has been registered, Salunkhe said, adding that investigation was underway.
