An 8-year-old girl was raped inside the Countee Cullen Library on W. 136th St in Harlem.

An 8-year-old girl was raped inside a public library bathroom in Harlem by a 13-year-old boy, police sources said Thursday.

The teen was being interviewed Thursday afternoon by detectives, the sources said.

He has not yet been charged.

The Wednesday afternoon attack happened inside the Countee Cullen Library on W. 136th St near Lenox Ave.

Sources said the girl was at the library with a caretaker and walking around, looking at books, when the suspect approached and somehow convinced her to go with him into the bathroom, where the attack happened.

The girl told her family about the incident, but not until she got home, sources said.

The relatives then called the police.