SPRINGFIELD, Ill. (WCIA) — Chatham Police are investigating credit card skimmers found inside two gas pumps Monday.

The skimmers were found at two pumps at the Shell gas station on 343 North Main Street in Chatham. Police officers believe the devices were installed within the last several weeks.

The devices have been collected by police and they are investigating the skimmer machines.

Police warn the devices are hard to detect and often have Bluetooth capabilities so criminals can retrieve information without going to the pump. They say it is a popular way of stealing credit card information.

To tell if a pump has been tampered with, make sure the pump is intact on both sides and check to see if. Also watch out for individuals parked besides pumps but not actually pumping fuel; skimming devices can be installed in under 10 minutes.

Some tips to avoid being scammed at the pump include paying inside, avoid using a debit card as it can give criminals access to your bank account, and don’t use a pump that looks like it has been tampered with. Police officials also say don’t put all your trust into security cameras at the gas station, as most videos are too far away or distorted.