"We believe that the weapon was an AK47 assault weapon," said Pinole Police Commander Pete Janke.
Commander Janke led the more than 50 police officers who rushed to Pinole Valley High School Friday. It was a massive response to reports a student had brought a weapon onto the campus. ABC7 has learned that one of two students arrested for having the assault weapon is a 14-year-old middle school student already on probation.
"There's a couple of probation violation charges, minor with a concealed weapon with a prior violation, and there is a charge for a minor possessing live ammunition with a prior violation," said Commander Janke.
In a six-hour search and lockdown of the school neither the weapon nor the ammunition was found, but police say they believe that the weapon had been on campus. Officers searched every student, back pack, and classroom.
"So it's still out there someplace so somebody else could get it and maybe finish off what they were going to do," said Gay Adams, a parent.
Adams anxiously waited hours for her daughter Sydne to be released by police and transported from the high school to a nearby grammar school, where she could pick her up.
"Columbine is the first thing that comes to mind, so you wonder how safe they really are," said Adams.
Sydne says what happened is hard to believe.
"It still has not set in yet. It happened in school. I don't know it's kind of weird," said Sydne.
West Contra Costa Unified School Board President Karen Pfeifer says that this is not an isolated incident. Every two weeks in a closed board meeting they expel at least one student for bringing a weapon on campus.
Pfeifer says the West Contra Costa School District acknowledges that guns continue to be a big problem for all schools.
"This does not surprise or shock me. I am very sorry that our kids are exposed to the idea that having an automatic weapon is somehow or another ok," said Pfeifer.
She says the school district takes the safety of its students seriously the size of the police response showed just how seriously.