ST. LOUIS -- Check your bank and credit card statements. Skimmers are popping up on ATM's in the Metro East and it has families worried about scam artists.

A skimmer was found on a ATM at Scott Credit Union in Waterloo, Illinois on Saturday morning.

Police believe only a small number of people might have used the ATM while the skimmer was in place. Police say a bank customer also found a skimmer on an ATM at the Scott Credit Union in the strip mall on East Washington Street in Millstadt, Illinois on Saturday.

If you bank at the Scott Credit Union or anywhere else for that matter, check your bank statements.

If something in your account doesn't look right, let police and your bank know.

What are skimmers?

A skimmer is a clandestine device designed to steal credit card information by “skimming” the magnetic strips on cards swiped at ATMs or gas stations. They’re often attached to the credit card slot on a gas pump or ATM, and sometimes they come complete with a camera that’ll capture you punching in your Personal Identification Number, or PIN.

Overlay skimmers

An overlay skimmer is one that fits over the card reader slot of an ATM or gas pump. For old or low-quality overlay skimmers, there are a few things you can look for.

The skimmer is usually modeled, or in some cases 3-D printed, to look like the part it's covering. However, it might not be the same quality or color as the rest of the machine. Maybe it's protruding a bit too far or isn't installed straight. If it looks like it doesn't quite fit or is loose, then that's a possible warning.

You can also look around for additions to the machine that could hide a camera pointed at the keypad. This is often how crooks get your PIN. It might be installed on the ATM, or even on the wall above it. Hackers have hidden cameras in fake outlets, lights and other things that wouldn't immediately catch your attention.

For these types of skimmers, it's actually fairly easy to defeat them. Simply cover your hand when you're typing in your PIN and the crooks won't have all the information they need to clone your card.

Advanced skimmers

Unfortunately for us, hackers quickly spotted the weaknesses of skimmers and have come up with options that are more difficult to detect. Some are actually impossible for you to catch.

A good example comes from Brazil. It's an overlay skimmer, but instead of overlaying the card reader, the entire front of the ATM is fake. See the unbelievable video.

The gas station thieves hid their skimmers inside the pumps. The skimmers were even equipped with Bluetooth so the thieves could drive by and extract the collected numbers and PINs wirelessly.

Another type of skimmer is thin enough that it fits right inside the ATM or gas pump's card reader slot. There's no external sign it's there, but it's busy swiping your info. This is what it looks like.

Unscrupulous employees of a restaurant or store might have handheld skimmers that you'll never see. Or they might put out POS terminals that are really skimmers in disguise; and they'll even print out a receipt.

So how do you protect yourself? Here are a few tips:

Anything look out of the ordinary?

Take a second at a gas pump or ATM and observe your surroundings — does the credit card slot or PIN pad look loose or out of place? Skimmers can be placed on top of the real credit card machine or inside the credit card slot. Try tugging at the payment terminal — sometimes skimmers come right off.

Check the other gas pump payment terminals — do they look like the one you’re using? Do a quick scan for anything that looks like a camera pointing at the pump or PIN pad.

Protect your PIN, if you use it at all

It’s best not to use your debit card with your PIN number at a gas pump if you can help it. If you must, cover the pad with your other hand while you punch in the digits, or simply pay inside. Fraudsters are less likely to tamper with a payment terminal at a clerk's counter.

Use bank ATMs, or those in well-lit, busy areas

While skimmers have been found on bank lobby ATMs as well, it’s less common. Thieves often target stations or ATMs that are off the main drag, or in badly lit areas.

Use a chipped card or other payment options

Almost everyone has a chipped, or “EMV,” card nowadays, and having one significantly decreases your chances of getting skimmed, because the data on the card is constantly changing and is difficult to extract. Bad news: Hackers get smarter all the time, and some point-of-sale terminals aren’t updated to allow the use of EMV cards. While not 100 percent fail-proof, using an EMV card makes it much harder to steal your personal info.

Payment methods like Apple Pay, Android Pay, or Samsung Pay allow you to make purchases without a card, which cuts out the opportunity for a physical skimmer to do its dirty work.

Keep an eye on your accounts

In any circumstance, it helps to watch your bank accounts for any odd or unusually large charges. You can set up text or email alerts to ping your mobile phone when charges hit your account — such as purchases made without a card swipe, or gas station purchases — allowing you to immediately address any potential fraudulent withdrawals.