ST. AUGUSTINE, Fla. -

Parents may deny it, but most teenage children admit they occasionally drink alcohol. 

A study of Florida teens found more than half of teens said they drink occasionally and one out of six admit to binge drinking.  Experts say alcohol is the most commonly abused drug by Florida teens.

Nearly a quarter of sixth graders say they've already had a drink of alcohol.

The question is, where do these underage drinkers get their booze?  Investigators know some of them buy alcohol at retail stores -- just like adults.

Channel 4 went undercover with local deputies to find out who is selling alcohol to teens in this area.  Law enforcement agencies regularly conduct stings -- sending in undercover, underage buyers to see who will sell to them.

Sgt. Mike Strausbaugh from the St. Johns County Sheriff's Office says it's about the sellers ignoring the law.

"We are, in conjunction with school district and (the Prevention Coalition of St. Johns County. We're trying to combat the problem of underage drinking in our community," Stausbaugh said.

"A lot of youth and the community have come to us and said, 'Underage drinking is an issue,'" said LeAnn Daddario, of the Prevention Coalition of St. Johns County. (PACT).  "We've decided to partner with the St. Johns County sheriff's office in an initiative to make sure retailers are not selling to underage minors."

Daddario’s coalition focuses on preventing underage drinking and drug abuse among kids. Aligned with PACT and utilizing a teen volunteer, the sheriff's office operates a sting on businesses in the county.

"So we want to see, every time we go out, retailers ask for their ID," Daddario said. "We don't particularly want people to get in trouble, we just want make sure the retailer is doing their part."

Strausbaugh trains an underage volunteer to go into a store and buy the same product with the same money at each stop. If asked, the teen agrees to offer their real ID, with their real age on it.

With Channel 4 in on a recent operation, the nervous teen strolled into a Kangaroo store on U.S. Highway 1 not far from the Sheriff's Office. Moments later, she strolled out with beer she had purchased. It was the first business she tried to buy from.

Once the teen operative buys and walks out with beer, undercover deputies already in the store work with a uniformed deputy to issue a citation. In some cases, the store has to close because the cited clerk is the only one on duty.

"This evening, the person who sold is in trouble," Strausbaugh said. "But ultimately, the license can be looked at by the state."

The undercover teen was surprised at how easy it was to buy booze.

"She didn't even ask me for ID. I thought she would at least do that," the17-year-old said. "She just glanced at me, I handed her the money, and I walked out!"

Strausbaugh and his team took the same scenario to 14 businesses in the area the day Channel 4 shadowed the operation. While a similar detail the week before found every business following the law and refusing to sell alcohol to the undercover, that wasn't the case the night Channel 4 rode along.

The next seven straight stores followed the law, but a clerk at the Hess Station near Interstate 95 and State Route 207 took the cash and handed over the beer.

Sanjay Patel, store manager at Hess Station, talked after receiving his citation.

"(This is) unusual. This is first time," Patel said. "It was kind of really busy. It just slipped out of my mind."