Something was a little fishy at Jonathan Law High School in Milford, Connecticut.

Kids were disappearing from class for longer and longer times, says Francis Thompson, the school’s principal.

“In the past year or so we’ve noticed an increase in the number of students going into the bathroom and they are spending more time,” Thompson told NBC News. “They were congregating. They were horsing around or sitting on sinks in the girl’s room and breaking them.”

He sent teachers to investigate. “What we found the common denominator was: They were vaping,” Thompson said.

This week, Food and Drug Administration commissioner Dr. Scott Gottlieb declared e-cigarette use an epidemic among teens.

He told manufacturers to come up with a plan within the next two months for discouraging teen use of vaping products, and threatened to ban all flavored vaping products.

Although some companies have said they were trying to make it clear their products are for adults only, Gottlieb said it looked to him more like an exercise in public relations and not a real attempt to stop selling to children and adolescents.

Thompson agrees.

“Companies like Juul claim to be investing in information to stop the teenagers from doing it, but it’s a big market for them,” he said.

Ads, he said, are have moved onto social media and he has no doubt who is attracted by lines of clothing made to conceal vaping devices with special pockets, fruity and candy-like flavors and celebrity endorsements.

“It’s definitely targeting this group of kids,” Thomson said.

And e-cigarettes are addicting a new generation to nicotine, pediatricians say.

Dr. Kirsten Hawkins, a pediatrician at Georgetown University Medical Center, says she is shocked at how quickly it is happening.

“It’s rampant among our high school and middle-school-age population,” Hawkins said. Many of her patients are already addicted to nicotine, she said.

“On one particular day in August, I had 12 patients aged 12 to 20 who said they were using Juul,” she said.

“One 12-year-old said he was bullied into trying it by his sibling and his friends. I found it fascinating that he did not realize the risks associated with a nicotine assistance device.”

Studies have shown that teens who try-e-cigarettes are far more likely to then go on to smoking old-fashioned combustible cigarettes. Hawkins saw it first-hand in a patient who lost her Juul device and became frantic in her need for a nicotine fix.

“She was smoking two packs (of cigarettes) a day,” Hawkins said.

I think it’s an epidemic and I think we are just catching on to it now so we are probably about five or six years behind the curve."

Teens are especially drawn to Juul because the device, which resembles a computer flash drive, is easily concealed. Unlike most other vaping devices that stream clouds of scented vapor, Juul emits short puffs that quickly dissipate.

This makes it difficult to detect even in class, Thompson said.

“Kids are concealing at home. They are doing it in classrooms and hallways, because teachers don’t know what to look for,” he said.

A person smokes a Juul e-cigarette in New York on July 8, 2018. Gabby Jones / Bloomberg via Getty Images file

And unlike with cigarettes, there is no telltale smoke or tobacco smell to alert teachers or parents to the culprit.

“The vapor disappears quickly and it’s masked by a scent such as mango, so you can’t tell if it’s someone’s new lip gloss or candy,” Thompson said.

Teens and adults alike mistakenly think vaping is harmless, pediatricians and educators have discovered.

“There is a misconception that they are only vaping water and that it’s healthy and that is not true,” Thompson said.

Teens may reject regular cigarettes as “gross,” Thompson said, but may not realize tobacco companies also sell vaping products. “They are still giving their money to Big Tobacco,” he said.

Plus, the flavored additives are made using potentially harmful chemicals, which vapers inhale into their lungs for thin membranes to absorb.

Some of the devices deliver a hefty load of nicotine, which decades of research has shown is highly addictive. It also can affect a developing brain in harmful ways.

As Hawkins found, many adolescents are already addicted.

“This is the next teenage epidemic and by the time we figure the long-term consequences out, a whole generation of kids, their health is going to be impacted,” Thompson said.

The American Academy of Pediatrics is equally worried and urges the FDA to do more.

“The AAP rejects FDA’s decision to allow five leading e-cigarette manufacturers to submit plans in 60 days for how they will address youth use of their products. FDA has the ability today to do what tobacco companies can’t and won’t do: take effective steps to reduce and eliminate youth use of e-cigarettes,” the group said.

“The Academy urges the agency to use its existing authority to immediately regulate all e-cigarettes. In fact, the AAP has joined other leading health and medical groups in legal action to compel FDA to do just that. If FDA continues to delay meaningful regulation, a generation of young people will become addicted to these dangerous products, which are being marketed to them in appealing, child-friendly flavors.”

Thompson said he is doing what he can to educate kids, teachers and parents about the dangers of vaping.

“When a student is found to be vaping or Juuling, our process is to give them some type of counseling program. We have counselors. Our nurses are involved. It’s a whole wrap-around service,” he said.

“Do I feel like it’s changing hearts and minds so they are not going to vape any more? No. I think it’s an epidemic and I think we are just catching on to it now so we are probably about five or six years behind the curve,” Thompson added.