The investigation is underway into how a gun was smuggled onto campus, who pulled the trigger and why.
It happened at Royal Sunset Continuation High School near the Hayward Airport and there has been an arrest.
Three teenagers were being questioned, and on Monday afternoon, one Royal Sunset student was arrested, but not for the shooting, but for illegally having a gun on campus.
The superintendent and sheriff deputies agree that nothing like this has ever happened before. They have cops on campus, they have deputies regularly patrolling, but still, somebody was brazen enough to bring a gun to school.
"I'm worried, I need to talk to somebody and find out if my little brother is in the school, or if they got all the kids out of here," said LeAndre Bradford.
LeAndre Bradford rushed to Royal Sunset High School after hearing about the shooting. It occurred at 11:00 a.m. in the boys' restroom. The victim is a 16-year-old shot once in the calf.
Investigators are still trying out to figure out exactly what happened.
"We don't believe this was a random attack where someone came in and started shooting. We believe the juvenile was targeted or it was some sort of accident," said Sgt. J.D. Nelson from Alameda County Sheriff's Department.
Dozens of Alameda County sheriff's deputies and Hayward police officers searched the school room by room looking for a gunman or gun, no weapon was found. Now questions surrounding security measures on this campus and how did a gun get in.
"We don't use metal detectors in our district, we haven't had a need. At this point in time it's a possibility that well look into something like weapons sniffing dogs coming in randomly," said San Lorenzo School Superintendent Dennis Byas.
Students were kept locked in their classrooms for about an hour just before school let out.
"I was scared. I was like okay, because we were all locked in a classroom. All I could do was call my mom," said Royal Sunset student Carmejia Evans.
An East Bay arts high school and a preschool were locked down while the search was underway for the shooter.
"When we were ready to walk them out, three sheriffs came in the front door with their guns drawn and said did anyone come through here. We were just stunned and we said no," said Royal Sunset Pre-School teacher Lisa Grace.
"I'm just like angered this could even happen, I'm angered," said Royal Sunset Pre-School teacher Catherine Wharton.
Wharton says she is mad at society in general. The superintendent told us the afternoon classes were cancelled, but he has let students know that it is back to school tomorrow.
A 17-year-old student is under arrest for illegally bringing a gun to school.