By Jim Smith

QUINCY (CBS) – Authorities continue to investigate a security breach at the Quincy Credit Union, a breach that gave hackers access to hundreds of accounts.

It was a busy day at the credit union on Monday as customers came in to get their accounts checked, and in some cases, get new ATM and debit cards.

READ MORE: At-Home Rapid Antigen COVID-19 Testing Gaining Popularity Ahead Of Holidays

WBZ found several customers who had anywhere from $500 to $1200 removed from their accounts by thieves.

READ MORE: 'This Is What Really Matters': Patriots TE Jonnu Smith Spreads Joy At Boys And Girls Club In Dorchester

“It was horrible,” said victim Kim Adams who lost $500. “I was working and taking money out to get some gas on the way from work and that’s when I found out so Merry Christmas to me. When I saw New York I thought maybe my husband bought me a Christmas present maybe from New York but no it was an ATM withdrawal.”

The credit union believes the breach has been isolated. Customers who had money stolen are being reimbursed in full. Authorities are investigating and want to make sure other banks are not hacked.

MORE NEWS: Families Being Forced Out Of Malden Apartments By Charter School That Purchased Building

Customers say the credit union has been every helpful with account holders.