If you filled up your tank at a particular Sharon gas station, police are suggesting you keep a close eye on your credit transactions.

Police Chief Edward Stabile tells 21 News that a credit card skimmer was discovered Thursday inside a pump at the Qwik Mart at 505 East State Street.

Investigators say they have no idea how long ago the skimmer was wired inside the pump which was not sealed with security tape.

According to the Federal Trade Commission, skimmers are illegal card readers attached to payment terminals to grab data off a credit or debit card's magnetic stripe without the user's knowledge.

Criminals sell the stolen data or use it to make purchases online. You won't know your information has been stolen until you get your statement or an overdraft notice.

Stabile says anyone who got gas at the Qwik Mart should monitor their credit history and notify their banks, credit card provider, and police if they believe they have been the victim of fraud.

The skimmer will undergo forensic analysis to try to find out who attached it to the gas pump.

To protect yourself, Stabile suggests that people remain vigilant for signs of tampering.

Ensure that integrity/security tape is fixed to the machines, and that the tape is not broken.

Cover the pin pad when entering a personal identification number.

Wiggle the credit card reader to make sure it isn't loose.

Any signs of tampering should be reported to the business.