The company operating Albertsons supermarkets in Southern California and elsewhere reported Friday that customers’ credit and debit card information may have been compromised by a data breach.

The company said it was not yet known if hackers succeeded in stealing customers’ card data.

AB Acquisition of Boise, Idaho, which runs Albertsons, said the company has contacted federal law enforcement officials, and computer forensics professionals are investigating. The company is also working with former Albertsons owners Supervalu, now the stores’ IT services provider to determine what happened.

Supervalu on Friday said that other retailers it owns have also been affected by the data breach. Supervalu had not confirmed whether any data had actually been stolen.

The breach likely occurred between June 22 and July of this year. Albertsons stores in California, Idaho, Montana, North Dakota, Nevada, Oregon, Southern Utah, Washington and Wyoming may have been affected by the breach.