St. Petersburg, FL -- Officials were still investigating an E-Cigarette mishap at Orlando’s Universal Studios Saturday that left two people injured.

RELATED STORY: Teen burned at Universal Orlando hospitalized, officials say

Officials say a man had one of the vapor devices in his pocket when it shot out a fireball injuring him and a 14-year-old girl who been riding the Hogwarts Express train that runs between the Harry Potter attraction in Islands of Adventure and the Studios side of the parks.

Todd Evans, who owns St. Pete Vape, showed us exactly how an e- cigarette could catch fire or even explode.

“That's a concealed battery,” he said, pointing to the internal power source - small, but powerful lithium-ion batteries.

“Car keys. Prime example. If you have these in your pocket loose this makes contact with them. You've got a short circuit. You know you can create a problem,” said Evans.

The batteries, says Evans, heat a coil that in turn turns liquid into vapor.

Rule number one, says Evans, keep e-cigs -- called mods -- and their batteries out of your pocket where they can contact metal, or even pressure against the power button.

The pressure may keep some models of the device from automatically shutting off.

“They do have safeties on them,” said Evans demonstrating the feature, “Five quick clicks do turn them on and off.”

The other safety issue that can lead to problems is inside the mod called the coils.

Alycia Singleton who operators Vapor Vault in St. Petersburg didn't mince words, showing us why she discourages customers from tinkering with those coils.

“Nine times out of 10, it is improper modifications to the mod,” said Singleton.

So why would anyone even do that?

Singleton showed us how modifying the coils can produce bigger vapor clouds by increasing the heat.

There are even competitions for blowing the biggest cloud of vapor, or blowing a cloud the farthest.

But the changes can also put huge stresses on the batteries. Draining, and possibly overheating them.

“You can pose a danger. I don’t want to say it's like a bomb, but it's very similar to it if you don't understand,” said Singleton.

Tampa General Hospital, which operates the Bay Area's busiest burn center, says fortunately they haven't seen any e-cigarette issues or tends.

Retailers believe FDA rules which took effect in August should also help curb the danger.