Christopher Gray, 27, faces numerous charges, including unlawful intercourse and lewd and lascivious acts with a minor.
The alleged crimes were reported on Tuesday, and a quick investigation led to Gray's arrest.
Police know of at least one victim, but they are working with the Manhattan Beach School District to find out if there are any other victims.
Gray is being held on $500,000 bail.
Anyone with information is urged to call (310) 802-5120.