CHARLOTTE, N.C. – A Caldwell County man was among those inside the Mandalay Bay Hotel in Las Vegas when the gunfire began Sunday night.

Lucas Bruch said he was on the hotel’s ground level during the shooting, and fortunately, he’s OK. He described the panicked moments when people began to realize what was happening.

“When the window exploded, I looked up and I saw glass falling down on the sidewalk and heard a few more gunshots,” Bruch said. “More glass broke and fell down.

“Then the music stopped and the screaming started and everyone was (screaming), ‘active shooter! We’ve got to figure out what to do.’”

According to Clark County Sheriff Joe Lombardo, 64-year-old Stephen Paddock was found dead inside his 32nd-floor room at the resort. At least 59 people were killed and another 527 were wounded during the deadliest mass shooting in modern U.S. history.

Bruch said he tried to call 911 multiple times, but the lines were clogged and he was unable to get through.

President Trump addressed the nation Monday from the White House, calling the attack "an act of pure evil" and ordering flags flown at half staff. He thanked first-responders for their "miraculous" efforts and said he would visit Las Vegas on Wednesday.

The three-day Route 91 Harvest festival started Friday, and Lombardo estimated that 22,000 people were in the crowd when the shooting began Sunday at about 10 p.m. local time.

The festival's headliner, country music singer Jason Aldean, was on stage when the barrage of bullets began and continued to play through the first, extended volley, video from the scene shows. The crowd appeared confused, unsure what the sound was.

The music stopped at about the same time the volley did, but after several seconds another, lengthy round of gunfire began, setting off bedlam in the crowd. Videos on social media show people ducking for cover and fleeing amid the unrelenting bombardment.

Cassie Manzanares, who was covering the festival for a Utah radio station, said she heard a "popping" noise.

"I've shot guns before, and it didn't sound like a gun," Manzanares said. "I thought maybe someone was doing firecrackers as a joke, or something happened with the pyrotechnics. But the next round (of gunfire) started, and that's when we heard the screaming."

Terrified, she said she froze. But a friend was shot, and she said she realized they had to run.

"We jumped over the wall and there were just bodies and blood and people screaming and trying to get away," Manzanares said. "People were breaking down fences to use to carry the bodies."