Thursday night there were graduation ceremonies for the senior class and one day later, police arrested a swim coach. A number of people connected to the school still hadn't heard about what happened.
Police picked up 25-year-old Joshua David Tatro of El Granada. He's been a swim and water polo coach at Aragon High School for the past year.
San Mateo police say they started their investigation about two and a half weeks ago. They say a female student who is a minor claimed that Tatro touched her inappropriately during the past year.
The alleged incident was brought to the attention of school officials who called San Mateo police. On Friday, Tatro was taken into custody and booked on one count of sexual assault on a minor and one count of lewd acts with a minor.
On Friday night the school board president had no comment on the matter. Police say they're working with the school district to make sure students are safe and they're asking anyone with relevant information about this case to come forward.