The "door knock" burglaries, as they're known, happen when a person knocks on the door and when no one answers, accomplices jump over a back fence and try to pry open the back sliding door.
"They're portraying themselves as some type of salesperson or repair person or a random person, just going around seeing if anyone is in their residence," Petaluma Police Lt. Tim Lyons said.
So far this year, between Jan. 1 and the end of June, there have been 28 home burglaries in Petaluma. This month alone, 18 homes have been hit.
"I've been here for 24 years and I've not seen this many property crimes occurring; this year has been incredible," Lyons said.
The revelation shocked neighbors who felt Petaluma is a safe city.
"We just have to be more careful and be on the lookout and I haven't been, I haven't been nearly enough," Pat Smith said.
"We keep everything locked up at night, we check to make sure that even the door to the garage to our house is locked," Patricia Reagan said.
Most of the burglaries are happening during the day. They're going through windows, side doors and open garages.
On Monday, police got a big break at the Adobe Creek Golf Course. A maintenance worker discovered a large amount of property hidden near the 11th hole. It turned out to be a stash of goods stolen by some of the burglars. There were power tools, sporting equipment, electronics, jewelry, laptops, even a coin collection. Police had to call a pickup truck to load all the goods.
Police have identified several suspects but say they believe there are several different groups working independently of each other.