It's a busy parking lot with people constantly going in and out of the fitness center in San Ramon, but on Monday night a thief or thieves managed to break the windows of at least 15 cars and steal the personal items inside.
People who use the lot regularly have heard about the occasional auto break-in, but never so many in one night.
"That's crazy, I mean generally I find this place pretty safe," said San Ramon resident Stacy Sibler. "I come here all the time and I never have any problems."
Earlier in the evening, there were six auto burglaries at Blackhawk Plaza while in Danville there were at least two at the Rose Garden shopping center.
Investigators from all three jurisdictions believe the break-ins are connected and they say only vehicles with items in plain view were targeted.
The thieves sorted out what they wanted to keep and dumped the rest in a different location.
"We found bags, clothing," said Michael Schneider of the San Ramon police told ABC7 News. "It appears what they ended up taking were mainly electronics, I think some sports equipment--that type of stuff."
Investigators are working on a few leads. They're reviewing video from security cameras mounted either at the shopping centers or throughout town.
People we talked to are now thinking twice about what they leave behind in their cars.
When asked if she should change her habits of leaving things around, Blackhawk resident Shirlane Lim said, "Based on what I heard today I think I should."