The supermarket chain Giant Food said on Tuesday that an illegal scanning device was found at the checkout of one of its stores in D.C., and that customers’ personal and financial information may have been stolen.

The device was found at one self-checkout point at its store at 1345 Park Road, in Northwest, Giant said in a letter to customers. It was discovered March 5 during what Giant called routine security procedures; Giant didn’t say how long the device had been there.

Giant said it has confirmed that no other store checkout points across any of its stores in the D.C. area have been compromised. It has notified law enforcement and engaged forensic experts to analyze the device.

The device was installed on one PIN pad and was capable of capturing data from payment card chips, but not from magnetic stripes, Giant said.

The personal information found on the device includes names, payment account numbers and expiration dates for a limited number of customers. The company said it has seen no evidence that any of the information has been misused.

Giant has notified potential affected shoppers it was able to identify .

“Since this incident occurred, we have further increased monitoring of all registers at Giant Food stores, including additional detection device tools, and will continue to be extra vigilant to protect customers,” Bob Bennett, vice president of Giant Food operations said.

Giant advises customers who may have been affected to monitor their account statements and their free credit reports.

WTOP’s Rick Massimo contributed to this story.