FORT DODGE, Iowa – It's a sport where punching, kicking and slamming a knee into someone's gut are allowed. And like it or not, its popularity has surged in recent years.
Known on the street as cage fighting (search), extreme fighting or mixed martial arts, it features a combination of wrestling, boxing and jujitsu.
The goal: Knock your opponent out cold ... or force him to surrender.
"I don't think it's that violent. It's the same in football, baseball and basketball — they all get injured just as bad. It's just a sport," Fort Dodge, Iowa, cage fighter Donnie Nordstrom told FOX News.
But others have a different perspective.
"It's very violent and somebody is going to get hurt very seriously. Somebody is going to get killed or maimed," said Iowa Athletic Commissioner Dave Neil.
So far, no cage fighters have died in the United States. But it may be only a matter of time, given the lack of rules and regulation at the lowest level of this combat sport.
"The only rule there really is in the state of Iowa is no hitting behind the head. No hitting in the kidney. And no slamming of the elbow if the person is down," Neil said.
Nineteen states have a set of unified rules for professional mixed martial-arts fights, but they seldom seem to apply to amateur contests.
There are approximately 10 states where the athletic commission regulates amateur cage fights. A handful of states flat-out ban it, and in all the others the athletic commission has no jurisdiction. That means there is no official oversight in most states, and promoters have the responsibility of keeping their fights clean.
That said, the highest level of mixed martial arts, known as ultimate fighting, is tightly regulated with well-defined rules — unlike the copycats.
Click on the video box near the top of this story to see a full report by FOX News' Jeff Goldblatt.