Passengers reported a sexual battery on the train. An officer intercepted the train and noticed that multiple passengers had the suspect detained. The officer contacted the victim, witnesses and the suspect and determined that the male suspect was seen rubbing his groin (clothed, but grinding) against the female victim. He was placed under citizen's arrest by the victim. He was issued a prohibition order and booked into the San Francisco County Jail for sexual battery. Train car video will be requested.