ALEXANDRIA, Va.—Police in Pennsylvania are dealing with an outbreak of skimmers. The investigation started when skimmers were found attached to ATMs at two separate 7-Eleven stores in Montgomery County, near Philadelphia.

On Tuesday, police announced that skimmers were found attached to c-store ATMs in four other locations.

“How it works: A small skimmer is inserted into the credit card slot, which reads the numbers on bank cards when they are inserted into the ATM. A tiny camera is hung above the keypad to capture PINs as they’re typed in,” a spokesperson for the Montgomery County District Attorney’s Office wrote. 

NACS provides resources to fight skimming, including training, decals and information.