LAS VEGAS (WFLA) — People who survived a mass shooting at a music festival in Las Vegas are struggling to process what happened right in front of them on Sunday night.

The massacre is being called the worst mass shooting in modern US history. At least 59 people were killed and 527 more were injured.

Brian Claypool, an attorney from Los Angeles, was in Las Vegas to celebrate his birthday. Claypool says he was supposed to leave Saturday but made a last-minute decision to stay an extra day to go hear some country music.

While talking to CNN’s Chris Cuomo, he got very emotional and said he’s feeling guilty about surviving. Claypool says he’s avoided seeing the victims and seeing the pictures of those who were killed because he was there.

“They’re a lot younger than me and they don’t get to go home,” he said. “I get to go home today, back to LA to see my daughter. And they don’t. I’m having trouble understanding that, comprehending that.”

After hearing about the heroic acts of others during the massacre, Claypool says he’s been asking himself if he did enough.

“Did I help enough people? Cause everybody was screaming and yelling. We didn’t know what to do. We didn’t know where the shooter was,” he said, choking back tears. “We thought he was going to jump over the fence. We thought there could’ve been one, two, three shooters.”

Claypool says there was a break after the first 30 seconds of shooting. During that time, a young man led him into a little room.

“I go in this room under the bleachers and there’s five or six young women, like 20, 22 years old and they were just on their knees and they were in a corner and they were crying,” Claypool said. “I just want to hope that I did enough to help them stay calm.”

“But at that moment, I’m feeling like it’s not fair,” he added. “It’s like you’re thinking that, is it fair for them to die, should I die? These are all going through your thoughts.”

Claypool says he stood out in front of them while they were down and hiding.

“Who determines who gets killed in this? That’s what I’m having trouble with,” he said. “Based on where you’re sitting, where you’re standing.”

He says a young woman in the general admissions section about 15 feet in front of him was shot and killed.

“I happened to be in an area where I didn’t get shot. So I guess I have to go the rest of my life wondering, why did some of these people die? Why didn’t I?”LAS VEGAS MASS SHOOTING COVERAGE: