CVS, the nation's second-largest drugstore chain says the site is being switched off as a precaution and that it has also sealed off related mobile device apps.

Payment information on the site is collected by an outside vendor, CVS Health Corp. says, and it's kept separate from its main CVS.com website and the computer system used in its pharmacies. Payments made through CVS.com and in CVS stores are not affected.

The online photo service sites for CVS, Costco and Walmart Canada are operated by PNI Digital Media, which suffered a hacking incident in 2014.

The companies wouldn't say how many customers could potentially be affected, but urged customers to check for any unusual activity on credit card accounts.

The Associated Press contributed to this report.