The incident was reported yesterday. The accused, Sarthak Kapoor (18) met the minor girl around 5.30 pm at the park. They had a scuffle and he attacked her, they said.
The accused panicked and went to his house, police said.
When the girl did not return home, her father approached the accused and his family to know the whereabouts of the girl.
Though he hesitated initially, Sarthak later admitted killing the girl, police said, adding he was arrested.
The matter is being probed, police added.