CHICAGO (CBS) — A string of car burglaries in the southwest suburbs has prompted one police chief to urge motorists to take a simple precaution: lock your car doors.

Palos Park Police Chief Joe Miller said there have been about 50 car burglaries in recent weeks in the southwest suburbs, and the thieves haven’t had to work very hard to get what they were after.

“They have not been breaking into cars. In other words, they haven’t been breaking car windows,” he said. “There’s video from us, there’s video from Orland Park, where they walk right up to your garage or your driveway, and they check your car door handle.”

In one instance, Miller said instead of just taking the contents of a car, they took the car itself in Palos Park, because it was unlocked and the key fob was inside.

One burglary team was almost caught early Sunday morning, but abandoned the stolen car they were using. The suspects got away, but police came away with clues about how they operate.

“We did find backpacks. We found flashlights, power bars. So it looks like what they’re doing is they may be dropping off individuals in certain areas, and they’ll simply walk up and down your block checking car doors,” he said. “They look like they’re going out for a camping trip for a couple of days, with their backpack and their equipment. So they know exactly what they’re doing.”

Miller said the thieves operate in the middle of the night, and have been focusing on suburbs surrounded by forest preserves, making it easy for them to blend in with the treeline if they see cars approaching.