Police arrested a 22-year-old Hauula man Sunday night as a suspect in a sexual assault case involving a 13-year-old girl.

The girl told authorities she was assaulted about 10 p.m. Saturday on the grounds of a Windward O'ahu school. Police did not name the school.

The suspect turned himself in about 10 p.m. Sunday at the Kahuku police substation and was arrested on suspicion of first-degree sexual assault.