Secret Service nabs dozens of 'skimmers' at U.S. gas pumps

July 3 (UPI) -- On the eve of possible record-breaking Fourth of July travel, the U.S. Secret Service is warning drivers not to get ripped off by thieves at the gas pump.

The agency has warned Americans to watch out for "skimmers" -- or thieves who steal credit card information by placing inconspicuous electronic card-readers at pumps.

The Secret Service said Tuesday agents are "leading the charge to protect the U.S. consumer against this growing cyber-enabled financial crime."

"Fueling stations are a prime target due the frequency of use and the criminal's ability to install the devices and recover the stolen data undetected," the agency said. "Gas pumps are typically unattended, developing suspects and making arrests in skimming cases is difficult -- but not impossible."

Customers can reduce their risk by paying with cash or paying with a credit card inside, rather than swiping cards at the pump.

Agents from 36 field offices participated in a nationwide initiative that nabbed nearly 60 illegal skimming devices in advance of the holiday.

"They'll take the stolen payment card number and will re-encode a gift card or credit card and then they will use that to buy electronics, gift cards, stuff that they can fence on grey market, the black market or the open market," Matthew O'Neill, of the agency's Criminal Investigative Division, told ABC News.

The Secret Service previously led a successful campaign that recovered more than 70 skimmers over Memorial Day weekend.

AAA estimates nearly 47 million Americans will travel more than 50 miles on July Fourth -- the highest number since it started keeping track 18 years ago.