we're onto you. You are watching what police say is a new breed of credit card thief caught on tape. They for a so called skimmer device installed inside this gas pump in arizona, stealing your credit... See More
we're onto you. You are watching what police say is a new breed of credit card thief caught on tape. They for a so called skimmer device installed inside this gas pump in arizona, stealing your credit card info when you think you're just paying for gas. What he doesn't know, according to investigators, is that he's just been caught in a covert sting operation. He put those in there and for whatever reason they're not there anymore. I know why, because I have them. Reporter: He's the one who tips us off. He's the one who switched out that skimming device for a night vision spy camera. We may have the first ever video of organized bad guys trying to retrieve their skimmers. Reporter: That video, gold. Here comes our producer pulling up to buy gas. He swipes his credit card and for all he knows an the gas station owner knows, crooks could be stealing from him right the then and there. He has no way of knowing. This is now a multi-billio dollar a year problem. That's where I found mine. Looking like this you can't see it. It looked like a match box. This man recently found a skimming device inside of his pumps. He's been in the gas business a long time and played us the greatest hits from his surveillance video collection. Used to come in here with a gun or break the windows at night when you were gone. Reporter: That is so last sentry. A skimmer wouldn't stick a gun in your face. There is nothing hiding his eyes but they will rob you blind. A skimming device found inside this pump sat there for months. He had no idea. Skimming all across the country got so bad that steve and the united states secret service, yep, the same guys who protect the president, are on the case. Are you winning the war? Right now we're doing our best. Certainly could use more help. Reporter: They're getting help from police departments, tipoffs, gas station owners and wait until you meet one of their secret weapons. Somebody turned my partner in and he turned me in. Dan is a reformed credit card hacker. He switched sides. He was caught by the secret service and spent two years training agents in the dark art of skimming. It's very easy and it's a lot of money. You can make tons of money. Gas station skimming is one of the easiest and best ways of doing it because it's hidden. It only takes seconds to open it up and put it in there. This is the reader that would be inside the gas pump. You would just swipe it through and it would read it right here. So you just add this into the circuit. That's exactly it. You would unplug this and you would just take the skimmer and plug it right back in. Nobody would know the difference. Reporter: But how do they get into the those pumps? Believe it or not, there is a universal key that opens most doors. That's the universal key? It's the same key from massachusetts to california. You can buy one online. Some of the newer devices use cell phone to transmit data. Then option number one is to sell your credit card number on a sort of ebay of skimmers. How much is my number worth? 5 to $30. Reporter: Geeze, not much. Are you nervous yet? Watch this. I would have an exact copy of your card. One swipe, that's it. That's option number two, clone a card. That's how easy it is to transfer your stolen credit card details onto a fake card. I was putting my own fake credit card and I would go to the store and purchase electronics and resell them. Reporter: So how do we stop guys like dan from going on shopping sprees with your credit card info? The arizona department of weights and measures is trying to stop this. We're checking for skimming devices. Reporter: It was when they found a skimmer in this pump that they had their bright idea, lay a trap. They pulled out the skimmer and -- we inserted one of these night vision spy cams in the back. 2:00 a.M. In a black suv pulls into the gas station picked up on the surveillance camera. Police tell us one guy blocks the attendant's view and bingo. Here's a view from that camera inside, a skimmer gang, police say. Apparently a man and woman team caught red handed. What we have here, we have the guys. And I have mrs. Guy. Awesome. Reporter: They can't find their skimmer and start bickering. Don't mess with that. It's like a husband and wife arguing about where is the car keys. Reporter: The cops are still searching for mr. And mrs. Skimmer but for our friend dan, his crime spree ended when he was spotted shopping aat a best buy with a fake credit card. Anything I wanted I would go out and get for free using these cards. Reporter: Dan's shopping sprees with counterfeit cards left a trail too easy to track. It's old fashioned. These days skimmers have a new way of turning stolen credit cards into cash. Normal truck on the road. You open it. Now it's not an ordinary truck. This is a 300 gallon container. Reporter: After installing these tanks, skimmers go back to the gas station filling them up at the pump paying for the gas with your stolen credit card. Look at the way this guy inserted the nozzle. It's so high it could access that secret compartment. They then transfer the gas to a regular tanker and make what looks like a ledge it delivery to a gas station owner. 8 million to $10 million a year. Reporter: The cops in l.A. County say they're pulling over trucks like this at the rate of one a week. What can you do to protect yourself and your digits? There is no point in looking at the pump for clues. You would never know. There is no way of knowing? No way. Reporter: While gas station owners are seeking new ways to protect their pumps, here are some things you can do. Check your account. Most credit card companies will suck up any loss if you report it within 60 days. Choose wisely. Choose a pump near the attendant. Skimmers prefer to target pumps in the shadows. And don't forget you don't actually need to put your card anywhere near the pump. You can always pay inside. We're about to put these
This transcript has been automatically generated and may not be 100% accurate.