Police and firefighters responded to a report of a fire at the school at 1200 Morello Park Drive at 5:49 a.m.
The fire was put out quickly and damage was limited to one building, police said.
Investigators determined that the fire was started in an outdoor garbage can near the building and had been burning for several hours before it spread to the structure.
A school employee discovered the blaze and called for help.
No injuries were reported, police said.
As of this afternoon, no suspects had been identified, police said. A damage estimate was not immediately available.
The case is still under investigation and anyone with information is asked to call Officer Patrick Salamid at (925) 372-3440.