SAN MATEO, Calif. -- A 22-year-old man is facing serious charges after sheriff's deputies say they discovered a pipe bomb in his car and more home-made explosives at his house in San Mateo. Edward Del Rio is being held in the Santa Clara County jail, and will most likely face felony charges.

The discoveries early Sunday morning forced the closure of Interstate 280 and prompted a neighborhood evacuation.

Neighbors returned from the long weekend to discover that their seemingly wholesome young neighbor might have been building pipe bombs in his parents’ garage.

Around 6:30 Sunday morning, Santa Clara County's bomb squad disabled what appeared to be a homemade explosive device at a house on Bettina Avenue, detonating it twice to make sure it wasn't live

Neighbors evacuated prior to the detonation said they had no idea what was going on.

“ I opened the door and [the police] said, ‘I can't explain but we'd like you to evacuate’,” said neighbor Miriam Silva.

“For the first hour and a half we didn't know there was a a pipe bomb across the steet,” said Len Silva.

Silva says he was shocked to learn the pipe bomb wasn't discovered across the street from his house, it was next door. His friend's 22-year-old son was allegedly responsible

“Nice kid. He graduated about last year, works for his father. We see him all the time. I saw him yesterday,” said Silva.

The Silvas say they believe Edward Del Rio's parents, were out of town this weekend, and may not know about their son's alleged activities.

They say they'll be heartbroken when they find out their only son is currently sitting in a jail cell.