Officers responded to a burglary alarm at the district's service building on Madera Avenue early Wednesday morning.
Investigators found a vehicle with no license plates parked near the building. Inside, they found burglary tools and stolen items from the school.
Officers also found 26-year-old Manuel Petatan, 24-year-old Raymond Islas, and 37-year-old Keisha Gomez inside the vehicle.
Detectives reviewed surveillance footage and said it shows the three suspects burglarizing the school.
Petatan, Islas and Gomez were later booked into the Madera County Jail.