Eric Paddock said the gunman was “just a guy” and speculated “something snapped” when he killed 50 people today.
The gunman, identified as 64-year-old Stephen Paddock, opened fire on a crowd of 22,000 at a music festival at Mandalay Bay Resort early this morning.
As well as fatally shooting at least 50 people, 406 revellers were hospitalised in the atrocious attack.
Now his brother Eric said he was in shock at his brother’s actions.
Eric Paddock, who did not regularly keep in contact with his brother, said he was now with their mother in Orlando, Florida.
He told DailyMail.com his brother hd showed “no indication” he was capable of carrying out such a deadly attack.
Mr Paddock said: “He was just a guy. Something happened, he snapped or something.
“He’s my brother, we don’t have a very close relationship but we talk occasionally. There’s no rhyme or reason here, it makes no sense.
“We have absolutely no idea. Our condolences go to the victims and all their families.”
He said the shooting was not a terror attack but could not explain why his brother had carried out the deadliest shooting in US history.
Mr Paddock said: “He has no political affiliation, no religious affiliation, as far as we know. This wasn’t a terror attack.”
He said his family were in shock and concerned at what could happen in the aftermath of the shooting.
Mr Paddock said: “Our family is OK, we’re sitting in here in our house hoping that everyone doesn’t attack us.
“My mother is 90 years old, lives down the street from me, we’re just completely dumbfounded.”
Thousands of panicked people fled the scene, in some cases trampling one another as law enforcement officers scrambled to locate and kill the gunman.
Shocked concertgoers, some with blood on their clothes, wandered the streets after the attack.
No other suspects are being sought after Stephen Paddock was discovered dead in his hotel room in Mandalay Bay.