Down East Credit Union said it believes skimming devices might have been used to access customer accounts.

For nearly a week, the bank and police officials have been investigating reports that tens of thousands of dollars were withdrawn from customer's accounts. The fraudulent activity was first reported Feb. 25 when victims noticed their accounts were nearly drained. In the intervening days, the bank has reissued cards and is refunding all losses that incurred as a result of the fraud. The bank said in a statement that it believes skimming devices were placed on two of its ATMs. Those devices are believed to have been placed on ATMs in Belfast and Unity.

"Our internal investigation is nearly complete and we will continue to work with any member that has been potentially impacted and ensure that they will be reimbursed for any losses," Joe Moses, executive vice president of the credit union, said in the statement.

Shortly after police alerted residents to the fraudulent activity, people posting on the police department's Facebook page reported losing several hundred dollars and many said they did not use the ATM at the credit union in town. Victims noticed a majority of the debit charges on their accounts were happening in New York while others were reported in Portland, police said.

Officials said the skimming devices have not compromised the bank's internal network or the credit union's security.

"We want to assure all of our members that their information is secure and at no time did a breach of our internal system occur. This is an external situation where the perpetrators accessed information from outside of the credit union's internal infrastructure,” Moses said.

Because of the fraud, the bank said it will make a “significant investment in the latest anti-skimming software, which it will install on all its ATMs. The bank said it would also continue working with police to determine if there are other safeguards it can implement.

Belfast Police Chief Mike McFadden said customers should continue to monitor their accounts and report any suspicious activity to the bank. Customers can call 1-800-472-3272 to have their cards blocked.

McFadden said the FBI and Secret Service is helping with the investigation.

Down East Credit Union, which is headquartered in Baileyville, operates branches in Bangor, Belfast, Calais, Machias, Richmond, Topsham and Unity.