SIMI VALLEY (CBSLA) — There are plenty of picturesque trails to hike along in Simi Valley. But police want to warn residents of the technology that’s being used to burglarize cars parked near hiking trail heads.

“It’s quite shocking, especially in this area you would find something happening like that,” said Simi Valley resident Dorina Timbal.

Simi Valley Police say it all started when an alert citizen noticed three men in their car acting suspiciously at Tapo Canyon Trail. She wrote down their license plate number and passed it along to police. Investigators say they later conducted surveillance on the suspects and watched them commit several car burglaries in Ventura and LA counties. All of them at trail heads.

How did they do it? Police say the suspects were using electronic jamming devices.

“What the suspects were doing is they would hold this button down. When this button was held down, vehicles within a certain distance of this jammer would not lock. It would prevent the fobs from locking the vehicles,” said Sgt. Patrick Zayicek, Simi Valley Police Department.

Zayicek says the sophisticated burglary tool was effective from a couple of hundred feet away — interrupting the signal from the victim’s remote key fobs.

“It was just some cars. It operates off a certain frequency and the cars that operated off the same frequency were the ones affected,” said Zayicek.

Police say they arrested three men who are from Chile, in the U.S. temporarily on visas.

Investigators say they recovered a lot of stolen property in their car.

Now police hope the public will prevent becoming victims of this tactic.

“Something we could do is we can make sure that we’re getting that audible horn from a car if that’s applicable to your car. The flashing lights because that wouldn’t happen if it was being jammed. Or simply just double checking that your vehicle is locked prior to leaving,” said Zayicek.

“So now knowing that, I think I’m going to be more aware of the people around me and what’s going on no matter if it’s in my neighborhood or no matter where I’m at,” said Timbol.