A St. George gun shop owner says he recently sold a shotgun to the man who killed more than 50 people and injured more than 500 at a Las Vegas concert late Sunday.

Chris Michel, owner of the Dixie GunWorx store in St. George, said Monday he recognized the 64-year-old suspect Stephen Paddock on the news, and realized Paddock had been in his shop before.

“When I got up this morning and learned this had happened in Las Vegas, it was just shock, horror and grief for the victims, questions about how this could happen,” he told the Tribune. “Then I recognized him, and my gut dropped out from underneath me.

“Immediately, I was trying to figure out if [the purchase Paddock made here] had any involvement in the shootings,” Michel added.

Stephen Paddock

As it became clear that Paddock had used a fully automatic weapon from a 32nd story room in the Mandalay Bay Hotel and Casino, beyond the range of a shotgun, that fear was alleviated.

“Still, there is the horror of what this was,” Michel said. “It’s still a gut-wrenching thing.”

Michel said Paddock purchased the shotgun from his store in late spring or early summer, passing all required background checks and even unspecified “additional measures” he requires under shop policy.

“There were no red flags at all,” he said, adding that the shotgun was only firearm sold by his store to Paddock.

Like many firearms dealers and buyers, Michel was shocked to learn Paddock had used a fully-automatic weapon, or machine gun, in the attacks.

“Class III” licenses required to legally own such weapons must be vetted by the FBI “and several other three-letter agencies,” Michel said, and the waiting period, even with approval typically takes up to a year to approve.

Dixie GunWorx, like other Utah gun shops, sells pistols, bolt- and lever-action rifles and some semi-automatic carbines — meaning single shots can be fired with each trigger pull — but not fully automatic weapons.

The Los Angeles Times reported Paddock had an arsenal of 19 weapons in his hotel room, primarily military-style rifles, and they had been brought in using several suitcases. The Times said several of the guns came from a Cabela’s in Verdi, with others purchased at Discount Firearms and Ammo in Las Vegas. Still others were bought at a store in Mesquite, where Paddock lived, called Guns and Guitars, according to USA Today.

David Familglietti of New Frontier told NBC News that Paddock purchased a rifle and a shotgun in the spring, and agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives were interviewing the employee who handled the sale.

“The rifle was not fully automatic and a shotgun isn’t capable of shooting from where he was,” Famiglietti told NBC when asked whether it was possible the guns were used in the mass shooting.