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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 50 people and injuring more than 400 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.”

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]."

Stephen Paddock 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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