Shoe and hat retailer Genesco this morning told customers and investors that its credit card processing system was hacked recently, but that it believes the intrusion has been contained.

Nashville-based Genesco said hackers breached the computer network that processes transactions for its Journeys, Journeys Kidz, Shi by Journeys and Johnston & Murphy stores, as well as some of its Underground Station locations, in the United States. Officials said it appears their other business units or Canadian stores were not affected.

It's possible that credit card numbers and expiration dates have been compromised, Genesco said, but unlikely that customers' Social Security numbers, names and addresses were exposed. The company has hired a computer security expert to help it assess the extent of the attack.

"Since we learned of the intrusion, we have worked diligently with outside experts to protect our customers' information and we are confident that they are safe shopping with their credit and debit cards at our stores," said Chairman, President and CEO Bob Dennis. "We recommend that our customers review their card statements and other account information carefully and immediately notify their card issuer if they suspect fraudulent use."

Shares of Genesco (Ticker: GCO), which are up 40 percent this year, were not active in pre-market trading this morning. They closed Thursday at $38.66.