MOST POPULAR: Video, stories and more
SIGN-UP: Get breaking news sent to you
Police arrested former Hillsdale student Alex Youshock after two of the bombs went off in an empty hallway at Hillsdale High. No one was hurt. Officers had to cut eight bombs off of the 17-year-old before they could take him into custody. They got him because three teachers threw themselves onto him and held him.
"The juvenile suspect arrived on campus right at about 8 o'clock at the start of the school day. The suspect possessed 10 explosive devices, homemade pipe bombs, a chain saw and a sword approximately 2 feet in length. The pipe bombs were attached to a tactical vest that the suspect was wearing," San Mateo Police Chief Susan Manheimer said.
The suspect detonated two pipe bombs in a hallway near the library.
The explosion set off fire alarms in the school. Two teachers who heard the explosion tried to confront the individual. A third teacher tackled the suspect to the ground as he was leaving. The suspect still had eight pipe bombs strapped to his body at the time.
Police responded within minutes and apprehended the juvenile suspect. The teen was a former student at the school.
Hillsdale High School is beginning its second week of classes for the fall semester with about 1,200 students.
Students said they knew something was wrong when the lights in the classroom went out and they heard a man in the hallway.
"The bomb went off and our chemistry teacher told us to get under our desks," said student Tyler Storozinski. "Then we heard the chainsaw trying to start. So our assistant teacher poked her head out and she saw a man with a chainsaw, so she closed the door and they made a call to the office and then we heard a second pipe bomb and then we got escorted out of the classroom."
"We heard two big explosions and so we walked out of the classroom and saw smoke coming in the classrooms and there was a guy coming with a chainsaw and a big fat knife or something like that," said student Justin Brown.
Students were evacuated to nearby Abbot Middle School. Parents were notified by phone about the incident and that no one had been injured.
"The kids are inside and they are OK. They just want to make sure that everyone is OK. We have to show ID to make sure that everyone is OK. I'm sorry I'm just really nervous," said parent Letty Priolo.
"It's scary. My daughter who graduated last year said they practiced this type of incident three or four times. So it's amazing how smooth this actually going. I'm happy about that," said parent Joe Stirlacci.
Police say a search of the Youshock home didn't help them figure out why he would want to bomb the school. His neighbors say they didn't suspect a thing.
"He never came outside. I only saw him once come outside to help his mom with the groceries," said Moses Molina, the suspect's neighbor.
These Hillsdale students got evacuated twice on Monday -- once from their school and then from their apartments, which are in the same building as the suspect's home.
"The cops knocked on my house and told us we had to get out because we were in danger," said Jennifer Arias, the suspect's neighbor.
Officers who searched the home say they did find materials used to make bombs. The details from the investigation so far are tough for parents to absorb.
Police say no one was injured by the blast. But the school needs to be searched thoroughly before classes can begin again Tuesday morning.
Earlier on Monday, Hillsdale High School has asked parents to check the district website for information about the campus reopening. The school will be closed on Tuesday and classes should resume on Wednesday.