ORLANDO, Fla. (FOX NEWS) -- The brother of the Las Vegas shooting suspect says there were no warning signs.

64-year-old Stephen Paddock opened fire on an outdoor music festival Sunday night, killing at least 58 people and injuring more than 500 in the worst mass shooting in United States history.

Eric Paddock told reporters outside his Central Florida home early Monday that his brother, who died of a self-inflicted gunshot, had no history of mental illness.

"We are completely dumbfounded," he said. "We can't understand what happened." He added that  "He bought the machine guns and he did this. I mean-- it was him who did this."

Paddock said his brother was "just a guy" and had retired to Nevada because he liked gambling. "We're lost," Paddock said. "I don't understand. It makes just no [sense]."

"Last time I talked to him was he texted me to ask how my mom was, after we didn't have power for five days in the neighborhood. He talked to her on the phone a week or two ago and then sent her a walker because she's having trouble walking," said Eric Paddock. 

When asked if his brother was a gun enthusiast, Eric Paddock said, "Never. He had a couple of handguns, I think. You know he had a safe with a couple of handguns. He might of had one long rifle, but he didn't have -- I mean he had no automatic weapons that I know, that I knew of  at any time"

Police say Stephen Paddock was a retired accountant who lived in Mesquite, Nevada, approximately 80 miles northeast of Las Vegas.

Authorities in Mesquite said he was a "mystery," and they had very little information about him. He was known to Las Vegas police, but only for a minor traffic violation.

Clark County Sheriff Joseph Lombardo said an "excess of 10 rifles" were found in Paddock's room on the 32nd story of the Mandalay Bay Resort and Casino, but he did not immediately reveal a motive. Paddock had been in the hotel room since September 28, according to Lombardo.

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