Ambler Borough police said the skimmers were found Monday by a service technician at three pumps at the Shell gas station on the 300 block of East Butler Avenue.
The pumps with skimmers were numbered 2, 7, and 8.
Police said any customer who used the pumps should consider canceling their card.
They should also check for fraudulent purchases in the bank accounts, police said.
"The Ambler Borough Police Department, Gas Company and Shell Gas Station are working together to prevent this from happening again in the future and this investigation is ongoing," police said.