At about 8:45 p.m., the Alameda County Sheriff's Office received a report of shots fired at the school located at 15980 Marcella St., near San Leandro.
When deputies arrived at the school they found a young man suffering from a gunshot wound.
The victim was transported to Eden Medical Center, where he died from his injuries, deputies said.
Homicide investigators are continuing to piece together the events leading up to the shooting.
This is the first homicide of the year for the Alameda County Sheriff's Office, according to deputies.