Chandler-based Bashas' supermarket chain says it's been victimized by a cyber attack on the stores' online systems, which provided criminals with access to customer payment information.
Bashas' officials say they recently located and removed a highly-sophisticated piece of malware from its systems.
They say victims have been limited to Lake Havasu City and Pinal County, but all customers are being warned to check their credit card and debit card transactions.
Forensic specialists and federal law enforcement officials have begun an investigation into the cyber attack to find those responsible.
Bashas' officials say they've installed additional security measures to protect customers' personal information from attacks in the future.
The company operates Bashas' supermarkets, AJ's Fine Foods and Food City.