The Sevierville Police Department and Tennessee Highway Patrol held an event Monday morning to warn the public of credit and debit card skimming devices at gas stations.

Authorities said there are three main types of skimmers.

1. Over the register card reader on ATM store machine: The surveillance video shows a man applying a skimmer in just seconds.

2. Outside the gas pump: The skimmer attaches over the card reader already installed. Authorities recommend trying to wiggle the card reader to see how much it moves since skimmers are usually attached with double-sided tape. If the card reader doesn’t move, it’s probably okay to use because card readers are built into the machines. Skimmers are externally attached.

3. Inside the pump: Authorities are most worried about skimmers inside the pump. A criminal would need to break into the gas pump, and insert a skimmer, which a consumer can’t detect besides knowing the safety tape on the pump door was broken into or resealed. Criminals using this technique can access someone’s card info from a computer near the gas station.

New technology makes skimming even more difficult to detect.

“They have Bluetooth connectivity to where once they get it in the gas pump, they can connect to it and pull the information out that way,” said Jason Brown, US Secret Service Resident Agent in Charge for Knoxville.

“You would see no performance changes in that gas pump and you would have no idea that it’s in there.”

Officials believe at least $25,000 was stolen using skimmers in the last several months throughout East Tennessee.

Authorities held the Monday morning event at the Pilot at 2150 Winfield Dunn Parkway. Authorities told 10News that Pilot is not a station with skimmer issues, but the gas station agreed to let them host the event.