LOUISVILLE, Ky. (WHAS11) – It hadn't been three hours into a four-day Las Vegas vacation for Louisville native Holly Kaller-Johnson and her family when they were walking the strip and heard chaos.

"My mom and sister thought it was fireworks and my brother-in-law said, 'No, it's gunfire.' They then heard everyone screaming, running and crying," she described to WHAS11.

They ran to their hotel, the Excalibur, just a few blocks from the shooting scene.

"They were just seeing people with blood on their shirts and crying and people in the elevator saying they just saw someone got shot," Kaller-Johnson recalled.

More than 500 people were injured and many of them were taken to University Medical Center. Traveling nurse Dean Harris, who is from Charlestown, Indiana, was on his first shift in the trauma unit.

"We had gotten so busy that we had to sit people with less severe injuries out in chairs in the hallway. We had to pull chairs out of patient's rooms - anywhere we could," he said.

Harris remembers treating a young man who thought was shot. "Dry blood all down his face. He said, 'Hey, can you tell me where I'm hit?' And I said, 'I don't know. Where do you think you're hit?' He pulls up the hair on his forehead and there was just like this line like a straw across about two and a half inches," Harris told WHAS11.

For Kaller-Johnson, guilt is on her mind. She says a family vacation that was supposed to be spent in the casinos seems inappropriate now, considering the brutal murders of nearly 60 people.

"I don't know if I should play game, gamble. I feel guilty. I don't feel like I should have a good time," she said.