An 80-year-old woman was allegedly raped by a 15-year-old boy at a village in Madhubani district of north Bihar, following which he was arrested, police said.
The incident took place at Jamaila village under the Andhrathadi police station limits late on Wednesday night, Superintendent of Police, Madhubani, Satya Prakash said.
He said the accused, who is a distant relative and a neighbour of the victim, allegedly raped the woman around midnight and tried to muffle her screams by forcing a piece of cloth into her mouth.
However, the cries of the victim jolted the members of her family and neighbours out of their sleep and the boy was captured.
They beat him up before being handed over to police, Prakash said, adding that he suffered serious injuries.
An FIR was lodged on the basis of a complaint made by the woman's daughter-in-law, he said.
"The complainant has claimed that the accused is an adult and his certificates which showed him a minor were fake. This would be ascertained through medical examination," the SP added.
The accused was sent to judicial custody after being produced before a magistrate, he said.