George Jakubec, a naturalized U.S. citizen who came from Serbia, was arrested last week. The 54-year-old faces dozens of bomb-making-related charges.
Authorities discovered the explosives after a gardener stepped on explosive powder in the backyard. He's still recovering from the blast that left him with eye, chest and arm injuries.
For the past week, Jakubec's next door neighbors have been unable to go home. Others have limited access to their homes.
"One night, I sat in my car for five hours outside, because I had no place to go," said Kate Johnson.
Bomb technicians have detonated some of the explosives.
"About every hour, there was a good explosion that we could feel rattling the windows," said Johnson.
Investigators uncovered 12 pounds of material used to make homemade bombs, detonators, blasting caps and unfinished shrapnel grenades.
"It's stable as long as no one is messing with it. So we're leaving it in there and we're going to disrupt it sometime in the future," said Asst. Sheriff Ed Prendergast of the San Diego County Sheriff's Department.
It's not clear what Jakubec was planning to do. He holds a private pilot's license and he's suspected of robbing two banks last summer. He pleaded not guilty to the robbery and bomb-making charges.
Bomb technicians must decide what to do with the remaining explosives. They're not expected to re-enter the home until next Wednesday.