The incident came to light on Wednesday afternoon when the girl complained of pain in her abdomen. She later told her parents that she was being allegedly raped by her 13-year-old friend, who lives in the same neighbourhood, for many days.
"The juvenile stays with his parents in a rented apartment in Govind Puri and studies in class 7 in a government school. He was caught from his residence soon after the victim's parents filed a complaint against him," a police officer said.
During investigation, it was found that the boy would enter the girl's house on the pretext of playing with her after her parents would leave for work and then allegedly rape her, the officer said.
"She has been admitted to Safdarjung Hospital and her statement will be recorded on Friday."
"The grandfather used to take rest on a cot outside the house. The boy entered our house on the pretext of playing and raped her whenever he found her alone," he said.
The boy has been sent to a juvenile home, police said.
Get the latest election news, live updates and election schedule for Lok Sabha Elections 2019 on ndtv.com/elections. Like us on Facebook or follow us on Twitter and Instagram for updates from each of the 543 parliamentary seats for the 2019 Indian general elections.