Eight teenagers have been admitted to Children’s Hospital of Wisconsin in the last month with extreme coughs, shortness of breath, and fatigue.

They arrived needing help to breathe and were quickly hooked up to oxygen masks and given steroids to help their lungs regain function.

Some had lost weight from vomiting and diarrhea . A Wisconsin man was put into a medically induced coma after arriving in the hospital with similar but more severe heart and lung damage.

The Wisconsin Department of Health Services has three epidemiologists and a team from two bureaus working on finding answers.

But there’s one thing that the eight teenagers have in common: vaping.

Although it’s unclear exactly what the teenagers had inhaled, according to the Milwaukee Journal Sentinel, they mentioned nicotine and THC, and the department is continuing to interview and investigate.

What is clear is that whatever they had inhaled was done through a vape pen, and it is damaging their lungs.

The hospital says seeing that number of patients in such a short time frame is concerning, CBS affiliate WDJT reports, and could be a sign of an impending vape-fueled healthcare crisis.

The news comes in the wake of Juul, the embattled e-cig startup, testifying in front of the House Committee on Oversight and Reform on Juul’s role in the youth vaping epidemic .

Eight out of 10 children don’t recognize that Juuls can cause harm, CBS reports from the hearing, and that belief may stem in part from Juul’s own marketing practices, tactics that Representative Ayana Pressley (a Democrat from Massachusetts) said “seem to be right out of the Big Tobacco playbook.” That’s not all that surprising considering the company sold out to Big Tobacco last year.