In what has become the worst mass shooting in modern U.S. history, a 64-year-old Nevada man repeatedly fired on a crowd Sunday night at an outdoor concert in Las Vegas with multiple weapons from his 32nd-floor hotel room, killing 59 people and wounding 527.
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The suspect, Stephen Paddock, committed suicide before police breached the door of his room at the Mandalay Bay Resort just after 10 p.m., according to authorities.
The attack took place as country music singer Jason Aldean performed before more than 22,000 people on the final day of the Route 91 Harvest Music Festival, just across the street from the resort.
Police told reporters at a news conference Monday they discovered in "excess of 10 rifles" in the room. A SWAT team, which broke in with explosives, found Paddock dead of a self-inflicted gunshot wound.
Police believe the shooter brought the weapons into the hotel room by himself and acted alone.
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A law enforcement sourced told Fox News that police found between 11 and 15 weapons in Paddock's hotel room, including converted, fully automatic AR-15 style assault rifles with high-capacity magazines.
Fully automatic weapons produced after the mid-1980s are illegal in the U.S., but those made before then can still be purchased with a background check by ATF and law enforcement notification. Some criminals have illegally converted semi-automatic weapons into automatic ones, however.
Monday afternoon, Las Vegas authorities told reporters they found ammonium nitrate in Paddock's car and tannerite explosives at his residence in Mesquite, Nevada, about 80 miles northeast of Las Vegas.
Law enforcement officials said many hundreds more could have died if not for the heroic efforts of first responders.
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Paddock had no criminal record, and his family is "completely dumbfounded."
ISIS is claiming responsibility for the attack, stating the shooter converted to Islam months ago. But no evidence has been provided. The statement, on the ISIS-affiliated Amaq news agency, called Paddock a "soldier of the Islamic State."
ISIS later issued a statement identifying Paddock as "Abu Abd Abdulbar al-Ameriki," reported Robert Spencer's Jihad Watch.
The FBI special-agent-in-charge Aaron Rouse told reporters Monday authorities "have determined at this point no connection to an international terror group."
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A video released by ISIS in June 2016 that praised Orlando nightclub shooter Omar Mateen also made specific threats against Las Vegas and San Francisco, PJ Media reported.
In May, an ISIS propaganda video emerged that called for a lone-wolf attack on the Las Vegas Strip.
Asked by reporters about a possible motive, Clark County Sheriff Joe Lombardo said: "I can't get into the mind of a psychopath at this point."
Las Vegas Mayor Carolyn Goodman, noting local hospitals were overwhelmed, urged Nevadans to donate blood to assist the wounded.
"What we ask for is blood," she said. "If our people want to do something, and they are healthy, then please donate blood. We'll have plenty of banks available. Always call a hospital if you're not sure."
The FBI is asking for anyone with videos or photos of the attack to call 1-800-CALL-FBI or (800) 225-5324.
Witness reports 'warning'
A witness, Breanna Hendricks, 21, told a local news station that about 45 minutes before the attack began, a woman and her male friend were escorted out of the concert venue after telling a woman everyone was going to die.
"She had been messing with a lady in front of her and telling her she was going to die, that we were all going to die," said Hendricks.
"They escorted her out to make her stop messing around with all the other people, but none of us knew it was going to be serious," she said.
Hendricks described the woman as Hispanic. Both the woman and her friend were around 5 feet 5 inches tall and looked like "everyday people," she said.
Family of suspect: 'We have absolutely no idea'
Paddock lived in an upscale retirement community in Mesquite with 62-year-old Marilou Danley, according to records.
Police located Danley outside the country and believe she was not involved in the attack. The Reno Gazette-Journal reported friends of Danley said she had been in the Philippines visiting family. Authorities said she was in Tokyo on Monday and planned to speak with her when she returned to the U.S.
Danley had worked as a hostess at the Atlantis Casino Resort and Spa, according to her Linkedin profile.
As the sun rose Monday morning, two blown-out windows could be seen on the 32nd floor of the hotel, with curtains flapping in the wind. Paddock had been a guest there since Thursday.
Eric Paddock, the suspect's brother, told DailyMail.com he was in shock after learning of the attack.
"We know absolutely nothing, this is just, we are dumbfounded," he said.
"We have absolutely no idea. Our condolences go to the victims and all their families."
Eric Paddock, a Florida resident, said he and his brother did not speak often, as they lived on opposite coasts. His brother, he said, had no political or religious affiliation and had never been "an avid gun guy at all."
He said their 90-year-old mother was "in shock" and struggling to cope with the news.
"You can imagine how this is affected her," he said.
Eric Paddock told the Orlando Sentinel their father was once on the FBI’s most-wanted list. Benjamin Hoskins Paddock, who died in 1978, was a bank robber who escaped from prison.
The FBI issued a poster at the time warning that the elder Paddock was "diagnosed as psychopathic" and "reportedly has suicidal tendencies and should be considered armed and dangerous."
CBS News, citing police, said Stephen Paddock recently had been gambling, including at the Mandalay Bay casino. NBC said Paddock had recently made a large gambling transaction.
Public records show he had a hunting license in Alaska, according to ABC. He also had a pilot's license and owned two aircraft. He worked as an accountant or auditor, according to ABC News.
Lockheed Martin said in a statement that Paddock worked for a predecessor company from 1985 to 1988.
"We're cooperating with authorities to answer questions they may have about Mr. Paddock and his time with the company," the statement said.
Trump: 'an act of pure evil'
President Trump, in a live address to the nation Monday morning from the White House, described the shooting as "an act of pure evil" and said he and the first lady, Melania, were praying for the families of the dead and wounded.
He ordered U.S. flags at the White House and public buildings to be lowered to half staff until sunset Friday.
Trump, striking a somber tone, said that while the attack provokes outrage, "it is our love that defines us today."
"Scripture teaches us the Lord is close to the broken-hearted and saves those who are crushed in spirit," he said. "We seek comfort in those words for we know that God lives in the hearts of those who grieve.'
The president, who will be in hurricane-ravaged Puerto Rico on Tuesday, said he will visit Las Vegas on Wednesday morning.
"We're going to be seeing the governor of the state, who I just spoke to, the mayor," he said.
Trump praised Sheriff Lombardo, "who has done such a great job."
"The police department has done such a fantastic job in terms of the speed, and we all very much appreciate it," he said.
In a tweet, Hillary Clinton declared it was time to "put politics aside" and then criticized the National Rifle Association, the Washington Times reported.
"Our grief isn’t enough," she wrote. "We can and must put politics aside, stand up to the NRA, and work together to try to stop this from happening again."
In another tweet, she suggest the toll would have been worse if the NRA had its way.
"The crowd fled at the sound of gunshots," Clinton said. "Imagine the deaths if the shooter had a silencer, which the NRA wants to make easier to get."
Singer Jake Owen, who was on stage when the attack began, said the gunfire lasted about seven to 10 minutes.
"It got faster and faster, almost like it sounded like it was an automatic rifle. You could hear it ringing off the tops of the rafters of the stage,” he told the "Today" show Monday.
"That’s when you saw people fleeing. At that point, everyone on stage just started running everywhere possible. It was pretty chaotic for sure."
Owen said he "just kind of ran like everyone else."
"At one point, I was crouched down behind a cop car with about 20 other people, that were people who had just come to the show," Owen said.
"Everyone’s asking if everyone's OK. There was blood on people. You can see a couple of folks in the street that looked like they had been shot, lying there."
Another witness, Russell Bleck, who was working at the concert, told Fox News "it was just relentless gunfire," estimating a duration of 15 minutes.
"It just didn't stop," he said.
Bleck described the scene as sheer panic, with no indication of where the shots were coming from.
Iraq War veteran Colin Donohue told "Fox & Friends" that "words can't describe" the horror, calling it worse than what he had seen during his deployment.
"We had a little bit up towards Mosul but nothing comparatively," he said.
"The first volley, nobody did anything, and then the second volley, everybody dropped," he said.
Other witnesses also said the music didn't stop until the second round of gunfire.
Donohue said he helped people get out of the line of fire.
"I just did what I was supposed to do and what I was trained to do, and I was trying to take care of people."
The wife of Sonny Melton, a registered nurse from Paris, Tennessee, told WZTV-TV in Nashville her 29-year-old husband was killed while protecting her.
"He saved my life and lost his," said Heather Gulish Melton.
'It was a massacre'
Kat Phifer, a barmaid at the festival, said she and three other people hid under a bar.
"Gunshots kept coming closer and closer, and we were all trying to keep quiet. Five seconds paused, then another round of shots. Closer and closer," she wrote.
"I was scared for my life. I was waiting for the bullets to hit us. Finally, the cops are yelling for us to run and leave. I run and lose all the girls I was with," said Phifer.
"While I'm running I see about five to seven people on the floor bleeding with people huddling around them. It was a massacre. I'm running for my life hoping not to get shot."
Jeff Bannerman of Ferndale, Washington, told the Seattle Times he took cover with his wife beneath concert bleachers.
"Jason Aldean was playing. It was a beautiful night," he said. "Then all hell breaks loose."
Bannerman said he and his wife were underneath the bleachers for 20 to 25 minutes.
He told the paper he called his children, who are 20 and 22 years old, from beneath the bleachers.
"My wife and I had to say goodbye to my kids," Bannerman said. "Oh my god. My wife's just beside herself. You tell your kids you love them, take care of yourself and your sister — what parent wants to do that?"
Tonight has been beyond horrific. I still dont know what to say but wanted to let everyone know that Me and my Crew are safe. My Thoughts and prayers go out to everyone involved tonight. It hurts my heart that this would happen to anyone who was just coming out to enjoy what should have been a fun night. #heartbroken #stopthehate