East Lyme — State police late Friday arrested a New London man who they said sexually assaulted a 15-year-old girl at McCook Beach in Niantic.

Gabriel Martinez, 18, of 44 Chester Street, New London, was charged with first-degree sexual assault, risk of injury to a minor, simple trespassing and breach of peace.

Police said the alleged sexual assault took place shortly before 11 p.m. Martinez was located at the scene and taken into police custody.

An investigation was conducted by East Lyme police and state police processed Martinez at the Troop E barracks in Montville. Martinez was released on a $20,000 non-surety bond. He is scheduled to appear in New London Superior Court.