Nicolas Ovendale, 20, was arrested near his Santa Clarita residence on one count of committing lewd acts with a child and one count of unlawful sexual intercourse.
"The responsiblity falls on the suspect in this case because he is 20 years old. He is an adult. They should be considering having relationships with people their own age, rather than children," said Los Angeles Sheriff's Sgt. Brian Hudson.
Late last month, Ovendale reportedly engaged in sexual intercourse with a 15-year-old female student inside his parked vehicle in the Stevenson Ranch area. Ovendale had come to know the victim after he was hired as an assistant coach for the freshman football team.
Detectives from the sheriff's special victims bureau began investigating the incident during the first week of November, when it was reported to Sheriff's Department personnel by school officials. Authorities said the student has confirmed the allegations.
A spokeswoman for the school district said Ovendale was fired after the allegations came to light, and the district is conducting its own investigation.
The school was closed Friday for Veterans Day, but students had already heard the rumors.
"I don't think it's right. I think it's wrong that a coach would hook up with a teenager in school," said student Bricia Lopez.
Ovendale was released from jail Friday after posting $50,000 bail.