LOUISVILLE, Ky. (WHAS11) -- Teenagers across Kentuckiana are turning to e-cigarettes and vaping devices and in many cases, becoming addicted before they're even 18.

We've shared their stories before. Oldham County students say it's a big problem in schools, but it's illegal to sell e-cigs and vapes to minors, so how are they getting them? We went undercover with police and local health officials in Oldham County to check in on which businesses are staying compliant with the law.

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"Honestly, I was expecting more to sell to me," one student, in the undercover operation said.

The La Grange Police Department and the Oldham County Health Department worked together and enlisted the help of teenagers to pose as buyers. They're able to do this through an annual grant through the state of Kentucky.

"Our role is security to protect the underage buyers that are going in and attempting to by tobacco products at these locations," Major Bruce Goodfleisch, with La Grange Police said.

Officers randomly selected 10 stores on a list and set out to see if anyone sold to minors. Once the officer was inside, one of two underage teens followed.

"I was standing out of the picture, but I could hear the transaction going on between them," Officer John Brooks, with La Grange Police said.

They had the cash in hand, but no ID.

"Do you have your ID with you?"

"No."

"Then I can't sell it to you."

One by one, these potential buyers walked out empty handed.

"In most cases, they would scan the item and then ask for the ID later," one teen said.

"Most of the bigger chains have their employees more trained and observant for this, because they're not relying on the business as much. The risks for selling, through licensing are greater, so they're a lot more vigilant about it," Major Goodfleisch said.

At the end of the day, we traveled through La Grange and Crestwood, checking in on a Marathon, Thorntons, Circle K, Walgreens and several food marts. All refused sales without an ID.

"I was a little bit surprised. I figured we'd have one or two sells. We were close a couple times," Goodfleisch said. "Most of our information comes from the kids. They're on the front lines. They know what's going on and it's their job to outsmart us. It's always a cat and mouse game."

RELATED: E-cigs, vaping included in Oldham County's smoke-free policy

Days after our investigation, La Grange Police revisited each of the 10 locations and rewarded the cashiers with a gift card to Dairy Queen in thanks for complying with the law. Had they sold to minors, they would have been given a warning.

We asked health officials if they knew of specific locations that may be more lenient on sales to minors without IDs.

"From the youth we've spoken with, it's coming from the shops in Jefferson, the ones that sit on the Jefferson/Oldham line," Anna Hobbs, the Health Education Coordinator with Oldham County Health Department said.

We checked in with Metro Police and Codes and Regulations and found similar compliance checks take place, with the knowledge of underage sales, but were told the focus in Jefferson County is on alcohol sales.

Learn more about Oldham County's health initiatives here.

â–ºContact reporter Brooke Hasch at bhasch@whas11.com. Follow her on Twitter (@WHAS11Hasch) and Facebook.