Ex-student arrested after school explosion

SAN MATEO, Calif. – A 17-year-old boy with a sword, a chain saw and homemade pipe bombs was arrested Monday after he detonated two of the bombs at a Northern California high school and was tackled by a teacher, authorities said.

The blasts caused no serious damage, and no injuries were reported.

The boy set off the bombs about 8 a.m. after walking into Hillsdale High School in San Mateo with at least 10 explosive devices attached to his vest, said police Lt. Mike Brunicardi.

The name of the boy, a former student, was not released because he is a minor, authorities said. Investigators have not determined a motive.

“There’s no question in our minds that this individual … may have caused grave damage, serious injuries and casualties,” San Mateo police Chief Susan Manheimer said.

The 1,200-student school was evacuated immediately after the blast, and classes were canceled for the day.

After the blasts, two teachers confronted the suspect, and a third tackled him outside an exit door. A principal joined them and held the teen for police, who arrived within minutes, Brunicardi said.

Brunicardi said the actions of the teachers, principal and police were “nothing short of heroic.”