Barnes & Noble has been hacked. The retailer said that there was "tampering with PIN pad devices" in 63 of its stores, all related to "one compromised PIN pad" in each location. In reaction to the tampering, B&N said it has stopped using the pads in all 700 of its stores.

B&N, which has notified federal authorities of the stolen information, said the scheme was a "sophisticated criminal effort" to steal the credit card information of its customers, but that, ultimately, the theft affected fewer than 1% of its PIN pads. The company added that its "customer database is secure."

News of the hacking first broke in various outlets Tuesday evening and B&N issued a release Wednesday morning that it is continuing to assist federal law enforcement authorities in this matter. In addition, B&N said, it is working with banks, payment card brands and issuers to identify accounts that may have been compromised, so banks and issuers can employ enhanced fraud security measures on potentially impacted accounts.

B&N said that purchases on Barnes &, NOOK and NOOK mobile apps were not affected. The member database was also not affected, and none of the affected PIN pads was discovered at Barnes & Noble College Bookstores.

For full list of the stores affected click here.