Lilburn, Georgia (CNN)-The man in the white shirt was pumping gas into an ordinary-looking white van. But he was no ordinary customer.

For one, it took him a long time at the pump. And then there were the stolen credit cards police say he took out of his wallet. In the 17 minutes he was at the pump, he used two cards to pump 95 gallons of diesel fuel.

What happened at this gas station outside Atlanta is part of a crime wave around the country, police say. It’s called “pump and dump.” Thieves use stolen credit cards to get gas and then sell it at cut-rate prices to truckers and gas stations that are part of the scheme.

Authorities say it’s a multi-million dollar crime with a quick payoff.

The criminals look as if they are pumping gas like any other customer. But their vehicles are vans, trucks and SUVs fitted with hidden tanks that can hold several hundred gallons. The hidden tanks range from sophisticated contraptions to a simple plastic or metal container inside the vehicle.

“It’s a very lucrative way to make money. It runs below the radar,” said U.S. Secret Service Agent Steve Scarince, who supervises the agency’s Los Angeles Fraud Task Force, and tracks the crime around the country.

Scarince said the gas theft rings in the Los Angeles area typically resell the stolen gas to gas stations for a fraction of the usual cost. The stations then sell it on — at full price — to the public. In other parts of the country, police have arrested thieves who resell the stolen gas to independent truckers or who use it themselves.

The crime typically starts with the thieves stealing credit card information or buying stolen numbers online. They then use those cards to buy gas.

But catching and prosecuting them can be a lengthy process.

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