Almost 40 credit cards in the Upper Peninsula have been compromised. The incidents happened within the past two weeks.
"We received some calls on Friday morning," said Marquette Community Federal Credit Union branch manager Dan Freberg. "People's debit cards being used that weren??t their transactions."
To protect cardholders, credit unions and banks are blocking credit or signature-based transactions.
"We know it??s an inconvenience for our members, but we're just trying to protect them and protect their money," Freberg explained.
Police and financial institutions believe that a skimmer could be behind the compromised information. A skimmer is a device that's put in a card reader at an ATM. Once you swipe, all the information is then saved from your credit card.
Police say a skimmer is just one of the ways this information can end up in the wrong hands.
"Physically, you can have your card stolen; you could enter the information on a computer on an unsecure website," said Detective Sgt. Steven Snowaert of the Marquette Police Department.
Cardholders are encouraged to check their statements often. If you spot any unusual activity, contact your financial institution immediately. If you're entering your card information online, make sure the website begins with 'https' --the 's' stands for secure.
Lastly, police say the best way to avoid being scammed is just pay with cash.