Police and fire crews were called to the scene about 9 on Monday morning on Fruitland Avenue at Winton Way.
That's right next to Atwater High School.
Fire officials say this building has been on fire several other times and for the safety of firefighters they decided to let the building burn and keep the flames from spreading.
In addition to the school, there is also a car dealership nearby.
Atwater residents are being asked to avoid the area while firefighters and police officers are on the scene conducting their investigation.