It's unknown whether packages containing crude pipe bombs sent to prominent Democrats and CNN were ever meant to explode, but while that investigation is underway San Diego bomb squads remain vigilant.
Locally, there are two bomb squads: The San Diego Fire Department’s squad covers the city while the San Diego County Sheriff Department’s (SDSO) team covers everywhere else in the county.
Bomb technicians with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and FBI are also notified when a suspicious package or device is reported.
The SDSO says its bomb technicians respond to about 125 calls involving suspicious packages or devices every year. About a dozen of those calls turn out to be actual explosives.
SDSO Bomb Squad Sergeant Greg Hampton told NBC 7 the cost of responding to these calls is not cheap. And while the county bomb squad's budget has stayed the same, the cost of equipment like protective suits and robotic devices has increased.
Still, officials say San Diego County is fortunate because between the SDSO, city, ATF and FBI, the county always has enough resources to respond to these types of calls.
Local bomb technicians said across the country, they've seen a rise in the number of cases involving homemade explosives. Investigators tell NBC News some of the devices used in these recent suspected mail bombs were most likely duds, with no possibility of exploding.
At this point, they say there's no way of knowing if that was intentional or just a product of bad design.
In a press conference Thursday afternoon, Bill Sweeney, Assistant Director at the FBI’s New York Office said, "This is a nationwide investigation involving multiple jurisdictions coast to coast."
The 2017 Annual Explosives Incident Report says California and Washington had the highest numbers of actual explosion incidents reported by law enforcement in the country last year.
SDSO and ATF spokespeople say the actual numbers are most likely higher.