NOWATA COUNTY, Oklahoma - Federal investigators believe a shot from a high-powered rifle may have ignited rubber debris on the range, starting a fire at one of Oklahoma's largest indoor gun ranges.

One customer died when witnesses say he went back into the burning building for his gun.

Alcohol, Tobacco and Firearm agents and the state fire marshal's office were on scene, investigating what happened.

A buckled frame and blackened metal, that's what the Nowata Firearms Range looks like after a fire started inside the indoor gun range Thursday afternoon.

Johnnie Swalley said he was across town when he noticed smoke in the sky. He said when he realized what was on fire he couldn't believe it.

“At first I just thought it was someone burning hay, you know, because it was so big," he said.

Most of the customers and employees made it out, but firefighters had to pull one man from the burning building; they said he died at a Bartlesville hospital a short time later.

Swalley said, “He came out, I was told, the fireman told me that, and then he said, ‘oh my gun's in there,' and he went back in and the smoke was so thick."

It was a stressful search and rescue; fire fighters said going into a burning building full of guns and ammo is always a risk.

Doug Sonenberg, with Lenapah Fire said, “Sure, every time, I mean that's always a concern."

Firefighters continued to put out hot spots into the evening as investigators arrived on scene.

The thought that someone lost his life is still something Swalley said he can't get over.

“You can replace guns. You can't replace a life,” he said.

Investigators also said the ammo inside the range was well contained and never went off during the fire.