Barnes & Noble said Tuesday that the company was hacked after devices used for swiping credit and debit cards in 63 of its stores across nine states have been “tampered with.”

The hacking incident occurred in nine states: California, Connecticut, Florida, Illinois, Massachusetts, New Jersey, New York, Pennsylvania and Rhode Island. Purchases online at Barnes&Noble.com as well as the Nook were not affected.

Barnes & Noble told customers Tuesday to check accounts for unauthorized transactions and suggested changing PIN numbers for debit cards. The company did not disclose if any accounts were hacked into but a company official told The New York Times that hackers indeed made unauthorized purchases on some credit cards. Barnes & Noble said it would work with banks and card issuers hacked to take additional fraud-protection measures.

The company said in an official statement that only of the devices called PIN pads were “tampered with” in each of the 63 stores. Spokeswoman Mary Ellen Keating said the problem was discovered last month

Authorities are helping in the investigation after Barnes & Noble disconnected the PIN pads in its 700 stores nationwide on Sept. 14. Until the issue is resolved, customers will swipe their cards on machines connected to the cash registers, which Barnes & Noble said is secure and safe.

The Associated Press provided a list of the 63 stories in nine states which were hacked.

California:

— 4735 Commons Way, Calabasas

— 2470 Tuscany Street, Corona

— 2015 Birch Road, Chula Vista

— 313 Corte Madera Town Center, Corte Madera

— 604 Bay Street, Emeryville

— 810 West Valley Parkway, Escondido

— 1315 E. Gladstone Street, Glendora

— 5183 Montclair Plaza Lane,Montclair

— 894 Marsh St., San Luis Obispo

— 2615 Vista Way, Oceanside

— 72-840 Highway 111, Palm Desert

— 27460 Lugonia Ave., Redlands

— 1150 El Camino Real, San Bruno

— 10775 Westview Parkway, San Diego

— 3600 Stevens Creek Blvd., San Jose

— 11 West Hillsdale Blvd., San Mateo

— 9938 Mission Gorge Road, Santee

— 40570 Winchester Rd., Temecula

— 4820 Telephone Road, Ventura

— 1149 S. Main St., Walnut Creek

Connecticut

— 470 Universal Drive North, North Haven

— 100 Greyrock Place, Stamford

— 60 Isham Road, W. Hartford

Florida

— 18711 NE Biscayne Blvd, Aventura

— 333 N. Congress Avenue, Boynton Beach

— 152 Miracle Mile, Coral Gables

— 1900 W. International Speedway, Daytona Beach

— 2051 N. Federal Highway, Fort Lauderdale

— 12405 N Kendall Drive, Miami

— 11380 Legacy Ave., Palm Beach Gardens

— 14572 SW 5th St., Pembroke Pines

— 11820 Pines Blvd., Pembroke Pines

— 5701 Sunset Drive, S. Miami

— 700 Rosemary Ave., West Palm Beach

Illinois

— 1441 West Webster Avenue, Chicago

— 1130 North State Street, Chicago

— 5380 Route 14, Crystal Lake

— 20600 North Rand Road, Deer Park

— 728 North Waukegan Road, Deerfield

— 1630 Sherman Avenue, Evanston

— 1468 Springhill Mall Blvd, W. Dundee

Massachusetts

— 170 Boylston Street, Chestnut Hill

— 96 Derby Street, Hingham

— 82 Providence Highway, East Walpole

New Jersey

— 395 Route 3 East, Clifton

— 55 Parsonage Road, Edison

— 2134 State Highway 35, Holmdel

— 4831 US Highway 9, Howell

New York

— 23-80 Bell Blvd., Bayside

— 176-60 Union Turnpike, Fresh Meadows

— 1542 Northern Blvd., Manhasset

— 160 E. 54th Street, New York

— 2289 Broadway, New York

— 33 East 17th Street, (Union Square) New York

— 555 Fifth Ave., New York

— 2245 Richmond Ave., Staten Island

— 230 Main St., White Plains

— 97 Warren Street, New York

Pennsylvania

— 100 West Bridge Street, Homestead

— 800 Settlers Ridge Center Drive, Pittsburgh

Rhode Island

— 1311 West Main Road, Middletown

— 371 Putnam Pike, Smithfield

— 1350-B Bald Hill Rd., Warwick