Police say the 17-year-old suspect was wearing a vest loaded with pipe bombs and was carrying a chainsaw and sword when he came to the Hillsdale High School campus Monday.
The 17-year-old former Hillsdale High School student who police say came to campus armed to the teeth Monday morning had been planning the attack for months, according to the San Mateo police chief.
Susan Manheimer told reporters the suspect intented to kill as many people as possible, adding Monday's incident could have been as bad as Columbine or other school attacks.
San Mateo County Assistant District Attorney Karen Guidotti announced Wednesday that she will try the suspect, Alexander Youshock, will be tried as an adult.
Classes were canceled Tuesday but are scheduled to be back in session Wednesday.
On Monday, the teenager armed with a sword, a chainsaw and 10 pipe bombs walked into the school. He detonated two bombs before being taken down by two teachers and the principal.
Students returned to school Wednesday. Teachers, students and others will gather to discuss the incident in the morning, then restart classes in the afternoon.
Classmates say Youshock dropped out of school last year and was a quiet kid who skipped a lot of classes. When he did attend school, they say, he didn't seem interested.
The suspect could be arraigned as early as Wednesday.
Police said they are recommending the following charges:
Police found eight more pipe bombs in a tactical vest the teenager was wearing when he was apprehended. He was also carrying a two foot sword and a chainsaw concealed in a violin case, according to police.
When he set off two of the bombs in an empty hallway, the smoke activated the school's fire alarm, San Mateo police Chief Susan Manheimer said. Two teachers heard the explosions, ran into the hallway and confronted the teen, who then fled.
A third teacher caught up with the teen and tackled him, police Lt. Mike Brunicardi said. Principal Jeff Gilbert and another teacher arrived a moment later and helped hold the suspect down until police arrived and arrested him.
Teacher Kennet Santana, 35, who is one of a number of Hillsdale staffers being hailed as heroes by police, told The Associated Press he was walking cautiously toward the disruption on Monday morning when he found himself face to face with the boy.
"He had a black tactical vest on with lots of pockets," Santana said by phone Tuesday. "We were maybe six feet away from each other at this point; we're talking seconds, there was not time for a lot of thinking."
Santana said the boy could have run toward the street to escape, but instead chose to follow the fleeing students.
"He was trying to go towards the kids, he could have exited to the street," Santana said. "He was trying to go towards the drama."
"I decided to close distance and bear hugged him and restrained his arms. We were face-to-face, chest-to-chest."
No one was injured in the explosion or in the subsequent arrest, Brunicardi said.
"The teachers acted heroically and risked their own lives," said San Mateo police Lt. Mike Brunicardi. "(They) were not taking into consideration their personal safety, they were taking the greater good into mind to save 1,270 students and about 100 school staff members.
"The potential for this incident -- 10 pipe bombs, a 2-foot sword and a chain saw -- indicate this could have been catastrophic" Brunicardi said.
Agents from the Agency of Alcohol Tobacco and Firearms searched his home and said they found bomb-making material.
"They did find materials consistent with making explosives, specifically pipe bombs," Brunicardi said.
Police flooded the campus of Hillsdale High School in San Mateo Monday morning. Students left the area by the hundreds after authorities canceled classes for the day following the explosions.
Police were called to the school just after 8 a.m. after reports that someone brought a gun on campus. While police were on their way, they heard reports of an explosion.
Kaela Murphy said is was really scary because she knew the suspect was right outside her classroom door. "He could have killed our whole class," Murphy said.
Parent Lisa Souther said when she got the news she immediately thought of Columbine. "That's exactly where my brain went. So it was scary, very scary," Souther said.
Santana said the boy did not struggle, only saying "Let me go" after he'd been held.
"He was not struggling, it was almost like he was defeated," he said.
"We had more people running to the explosion than we had running away from the explosion," principal Jeff Gilbert said. "So I think that speaks to the staff and just what they feel about the students."