(CNN) At some point Thursday, Stephen Paddock checked into the Mandalay Bay Resort and Casino on the Las Vegas Strip.

He'd driven 80 miles from his home in Mesquite, on the Nevada-Arizona border, for ... what, exactly, no one knew.

And yet, here he was, holed up in room 32-135 with 23 weapons, multiple rifles -- some with scopes on them -- and a cache of ammunition. He'd brought them in in more than 10 suitcases.

Across the street, a three-day country music festival would kick off that weekend. The gilded windows of his 32nd-floor suite would offer him an uninterrupted view.

He waited.

The lineup for Route 91 Harvest was a who's who of country music talent: Eric Church. Sam Hunt. Big & Rich. All weekend long, fans packed the sold-out festival, drinking, partying and singing along.

The scene at the festival on Saturday, the second night.

Now it was 10 p.m. Sunday and the 22,000 concertgoers who remained were there to end their jamboree with Jason Aldean, the final act.

Up on the 32nd floor, Paddock smashed two windows in his hotel room with a hammer -- one in the front and one in the corner. He picked up a gun, took aim at the fans below, and opened fire. Bullets rained down.

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For a few seconds, no one seemed to react. The intro riff to Aldean's "When She Says Baby" had just ended , no one seemed to react. The intro riff to Aldean's "When She Says Baby" had just ended when the sound of automatic gunfire filled the air . It wasn't until the third line -- "Some days I'd rather be a no show" -- that Aldean realized something frightening was happening. He darted to the back of the stage.

For the next 10 to 15 minutes, it was full-blown panic for the 22,000 attendees. They scrambled for cover and hid under bleachers. They jumped over fences and shielded loved ones with their bodies.

The guy down in front of us, about 10 feet up, goes down. The guy to the right of him, about 3 feet over, goes down. Ben and I both look behind us -- two girls go down. And he says 'Run!' A concertgoer

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I put the baby on the ground and got on top of her. And when we heard a little break, we ran to the bleachers that were just behind us I tried to tuck her as close to the end so she was as protected as possible. Carly Krygier

People flattened on the grass. And every time there was a temporary break in the gunfire, they'd get up and sprint for cover. Again and again and again.

Every time we heard shots, we'd hit the ground and just stay there until they would stop for about 30 to 45 seconds. And then we would run as fast as we could. ... I thought the shooting would never end. Shelly Mallory

It felt like eternity. But a SWAT unit swiftly and methodically worked its way up the Mandalay Bay, floor by floor. It cleared out the 29th floor, the 30th, the 31st. "I'm inside the Mandalay Bay on the 31st floor, I can hear automatic fire coming from one floor ahead," one of them radioed in. "One floor above us." The team headed to the 32nd floor. Paddock shot through the doorway, firing at officers. They stopped. They were about to blow open the door.

We have sight on the suspect's door. I need everyone in the hallway to be aware of it and get back. We need to pop this and see if we get any further response from this guy to see if he's in here or actually moved somewhere else.

They were too late. Paddock had killed himself, leaving behind a whole host of questions. Chief among them: Why?

ISIS was quick to claim credit -- but officials aren't convinced.

"I can't go into the mind of a psychopath," Las Vegas Sheriff Joe Lombardo said. "We have to establish what his motivation was first."

Slowly, . Victims such as Jenny Parks, a kindergarten teacher. Or Sonny Melton, a registered nurse, who was at the show with his wife. She survived. He didn't. the names of the victims are surfacing . Victims such as Jenny Parks, a kindergarten teacher. Or Sonny Melton, a registered nurse, who was at the show with his wife. She survived. He didn't.

At least 59 dead. Some 527 injured. . Some 527 injured. The deadliest mass shooting in modern US history . Yet another addition to a sad and growing list: Pulse, Virginia Tech. Sandy Hook.

Those who were fortunate enough to make it out alive may never be quite the same.

"This is all other people's blood," said one woman, pointing to her legs. "This is all blood splatter from people being dead and us having to be on top of them basically to get out."

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The blood will wash away. The psychic scars may not.