ASPEN, Colo. - Aspen Police are trying to determine who put a skimming device on an ATM inside a bank lobby.

A skimmer is a small electronic device that copies the data from ATM cards and credit cards inserted into an electronic device such as a gas station pump or ATM, police explained.

Officers believe the ATM at the Aspen bank was comprised between Dec. 22 and Dec. 29.

"Because we are aware that criminal activity was occurring in town, it is possible that other credit card readers may have been similarly compromised," said Detective Walter Chi. "We recommend that everyone check their bank accounts for fraudulent activity, and continue to monitor them."

Police said the bank where the skimming device was found has notified its customers and issued them new cards.