(HARBESON, Del.) - A third credit card skimmer has been discovered at the Exxon Mobil gas station located off Lewes-Georgetown Highway.

Laurie Childers, owner of Harbeson Deli, says the skimmer was found early Thursday afternoon. She says numerous customers alerted staff after noticing fraudulent activity on their bank accounts.

"Last evening, approximately around 7:30 or 8 p.m., we had a few customers mention that there was a possible problem with their bank accounts after using the pumps the previous day. Then this morning we immediately had another customer say something to us, so we contacted our company that services our gas pumps and they came out and found a skimmer on pump four," explained Childers.

Skimmers (or skimming devices) are often used by criminals in order to steal unsuspecting victims' credit card information. They're most commonly found in gas pumps and ATMs.

"It looks like part of the gas pump so it's hard to tell it's even there," said Childers. "You'd have to really know what you were looking for in order to find it."

Unfortunately, this isn't the first time a skimmer had been found. Childers says two other skimming devices were discovered about eight months ago on pumps '2' and '4'.

"We have safety strips on our pumps that we check daily and if they tend to be compromised then we generally call and have the pumps looked at, but unfortunately this time they weren't," said Childers.

Childers says all the pumps are now safe to use.

"Everything is fine as of right now. Certainly though, at any time, unfortunately, someone can put a device like that on the gas pumps," said Childers.

Anyone who recently visited Exxon is reminded to keep a close eye on their bank accounts and report any suspicious activity to their banks.

Some ways to avoid credit card skimmers include paying with cash or going inside to pay with a card. If you must use your card at the pump, use a gas pump that's in clear view of the cashier. Officials say those pumps are less often targeted by criminals. In addition, check to see if any safety seals or stickers have been tampered with. If so, chose another pump and alert staff right away.