The placement of skimmers at gas pumps has been going on for years, but according to the Secret Service, they have seen an increase in the number of hacked credit card readers.

Reports of skimming incidents in Brownsville, Mission, Harlingen and McAllen are currently under investigation.

A skimmer is a device attached to a payment terminal, like cash registers, and in recent cases, the inside of gas pumps.

The device is used to collect information on a debit or credit card, including the pin.

The Secret Service says criminals have been using the card numbers to purchase gasoline outside the area and access ATM machines.

While skimmers can be difficult to detect, John Saenz, PIO for McAllen Police Department, advises consumers to physically inspect payment terminals before making a transaction.

“Wiggle the card reader, if there’s any signs of tampering, obviously report that to the attendant that’s at that location,” said Saenz. “Any signs that a panel at the gas station had been pried open or if a security strip has been removed or tampered with, do not use that terminal.”

It’s also recommended that you pay inside the store or choose a pump that is close to the store.

Another tip is to cover your pin while you enter the number because some of the devices used have become very sophisticated like pin hole cameras which allow criminals to steal your information.

Saenz adds that you should frequently monitor your bank account because the faster you identify some type of fraudulent activity on your account, the quicker law enforcement can locate those responsible.