CHARLOTTE, N.C. -- Trampoline parks are growing in popularity around the country, but in most states like in North Carolina, they’re loosely regulated.

It means parents must be extra vigilant when watching their kids.

Nationwide, there are 600 trampoline parks, 15 times more than there were six years ago. They make up a $300 million industry. Only three states require annual inspections and liability insurance to operate. Three other states are debating legislation right now.

NBC Charlotte checked with lawmakers in Raleigh and there are no current plans for regulations here.

“Anyone watching here today can call the franchise and open up a trampoline park at any shopping center or warehouse and start bringing in patrons and making money,” said Michael Gomez, personal injury attorney based in Texas.

The Consumer Product Safety Commission estimates park injuries increased from 600 in 2010 to more than 6000 in 2014. NBC Charlotte compiled some number from Medic and found among four local trampoline parks Medic’s been called 23 times in the past year. Sixteen of those injuries were serious enough to involve a trip to the hospital. Medic says those numbers aren’t abnormally high for a high-traffic area.

Some trampoline parks belong to professional organizations that require certain safety protocol. But those standards are enforced by any city or state law.