Similar to what criminals do at ATM machines, this is done at some gas pumps as well. A small device is attached to the credit card insert at the pump, reading your card’s info the second you stick it in.
The criminals come back to the pump in secret later on and even use Bluetooth technology to download all the information from the skimmer without ever leaving their car!
How to avoid: always pay attention to the plastic you put your card in. If it looks suspicious and is a skimmer, it should be easy to remove-- try it! Then inform the police.