CASTRO VALLEY (KPIX 5) – Safeway is investigating the possibility of thieves placing card skimmers at several grocery stores. A report claims that two stores in the Bay Area could have been impacted.

According to the Krebs on Security blog, banks began to notice their customers had their accounts emptied after shopping at some Safeway stores. The alleged skimming reportedly began in September.

Bank industry sources told Krebs the fraud may involve Safeway stores in Castro Valley and Menlo Park. Safeway stores in several Colorado locations may also be affected.

In a written statement, Safeway denied that Castro Valley and Menlo Park stores were involved, but said they found two skimmers at stores in Dublin and Walnut Creek back in September and have not discovered any since. Safeway said no card data was compromised by those skimmers.

“Like all responsible business owners, our store teams routinely inspect all point of sale devices and discovered the two skimmers during these inspections,” the Pleasanton-based chain said in a statement released Wednesday afternoon.

Krebs reported that the thieves may have either installed devices that captured PINs and debit card data or secretly swapped out existing credit card terminals with ones that were compromised. It appears the thieves targeted specific checkout lanes at stores.

“I was thinking about using my checkbook. Of course, every one behind you in line would be annoyed, but it’s safer,” said Colleen Costa, who was shopping at a Safeway in Castro Valley on Wednesday.

KPIX 5 has reached out to authorities in Alameda County and San Mateo County for comment.