Authorities on Tuesday charged a 30-year-old staff member at McKinley High School after a 17-year-old student told police that he sexually assaulted her on two occasions, including Friday in a classroom.

Gregory Keau was charged with first-degree sexual assault. His bail was set at $75,000.

In a court affidavit, police said Keau, a special-education assistant at the school, was assaulting the student when another staff member walked into the room, saw what was going on and confronted Keau.

The co-worker reported the incident to school officials, and police were called. Keau left the campus before officers arrived, but turned himself in Sunday at the main police station.

Police said the girl said Keau also assaulted her when she was a 16-year-old sophomore.