EAST WALNUT HILLS, Ohio (WKRC) When you lock and unlock your car with a "key fob", you never know who could be nearby waiting to grab the signal.

Thieves are using key fob hacks to get into vehicles.

Several weeks ago, Jessica Haynes and her husband heard their car starting in the middle of the night.

“Marion jumped out the bed and looked out the window, and our car was driving down the driveway and so he got up and got clothes on and jumped in our other car to try to follow him and I called the police," said Jessica.

The Haynes’s got their car back, but the thief got away. Jessica thinks he used a device to grab the signal from the fob in the kitchen.

"We thought that we had left the car door unlocked, but then later we’re hearing about these ways to extend key fob signals and our kitchen is like right next to where our cars are parked," said Jessica.

Cincinnati Police are seeing more reports of car thefts and things stolen from locked vehicles. Sergeant Eric Franz says there are two ways thieves can use a device to steal a signal from a key fob.

“They watch you unlock and lock a car. They grab the signal. They know it’s yours. You go away and they’re able to clone the signal using their laptop and a small transmitter to unlock the car,” said Franz.

Franz described how keyless fobs with RFI chips can be hacked.

“They’ll hold a backpack up to the window and try to grab your signal and the second person’s at the car and when it connects, the door unlocks. They get in the car, and press the start button," said Franz.

Since the theft, Jessica invested in a signalblocking bag. She and her husband store their keys in it and haven’t had any problems.