SEARCY (AP) — A 48-year-old Searcy police officer who worked as a school resource officer has been arrested in the bedroom of a 16-year-old girl.

Arkansas State Police spokesman Bill Sadler says state police agents were waiting in the room when Hamilton Riley entered through a window about 1 a.m. Tuesday and arrested him for felony first-degree sexual assault.

Riley submitted a one sentence letter to the police department about 7 a.m. Tuesday saying he is resigning immediately "due to personal reasons." He was later released on $100,000 bail. He could not be reached for comment.

Prosecuting Attorney Chris Raff says Riley was a resource officer at Ahlf Junior High School in Searcy. He says Riley and the girl met at school.

Searcy police say only that they are cooperating with the investigation.