The Centers for Disease Control and Prevention is advising e-cigarette users to consider stopping while they investigate at least three deaths believed to be linked to the cigarette alternative.

"We are observing directly a change in the airways and blood vessels in the scar and lung tissue,” says Paula Cupertino Hackensack Meridian Health. “Remember this product, they go very fast to the lungs and the lungs have a very large superficial area and it gets absorbed immediately into the brain."

But despite linking this illness to vaping, narrowing down which product is causing the illness is still part of the investigation. The CDC says that some patients used products with THC in them, while others just used nicotine.

“An initial factor here that we can't forget is that electronic cigarettes, most of them, especially the ones that are being consumed, are not regulated so we don't know what's in them,” Cupertino says.

But some vape shop employees say that while the warnings are alarming, they want to see a bit more information.

Tri-State Vapors employee Nick Downey says that he is worried because these types of products can be bought online.

“Where it comes from? Who it's coming from and what have they done to it? Because you don't know, you really don't. You don't know who you're buying from. Is a sketch ball or some weird person trying to hurt somebody? You really don't know what they're adding into their stuff,” Downey says.

The CDC advises vapers to not buy their products off the street or alter it in any way. They also say to report any symptoms related to vaping to a doctor immediately.