They stood opposite the Mandalay Bay Resort and Casino, listening to the music, as 64-year-old Stephen Paddock unleashed deadly gunfire on the crowds from the 32nd floor; killing 58 people and injuring more than 500.
When the news hit international headlines their family in New Zealand scrambled to contact them and were "absolutely relieved" to hear they were safe.
Rosemarie's daughter, Helen Buckingham, said she managed to make contact with Mr Parks by 11.20pm Monday night.
"At first we couldn't make contact last night, my aunty rang their hotel room but couldn't get through. I just happened to be messaging my stepfather on Facebook messenger and noticed he went active so I rang straight away and they were in lockdown."
The conversation, sparse on detail, informed the family the couple were safe but in lockdown and being slowly moved from building to building down the strip by police.
Mrs Holmes said the sight of the injured had traumatised her daughter.
"They took a stretcher past with a woman on it who was all bloody so she was a bit upset about that.
"I was very relieved to hear they were safe. They travel every year and there's just so many things going on in the world now. I often think I hope they don't get involved in anything," she said.
They had been holidaying with Mr Parks' daughter and her boyfriend, Glenn Read, who were about 500m away from where the gunman began shooting.
Mr Read they were about to embark on a night helicopter ride over Las Vegas when the chaos broke out.
"We were about to do a helicopter ride over Las Vegas when people started running through the front door panicking. One was shot in the arm, it was crazy."
He said people were put in a locked helicopter hangar but they weren't listening and panicking.
They were later moved to a private plane waiting room 1km down the road before being able to return to their hotel in the early hours of the morning.
Mrs Holmes said her daughter was worried about catching a 5am flight bound for Florida.
"They were just in a predicament where they were up one end of the strip, by the Mandalay, and their hotel the Stratosphere is right down the other end.
"When they were being guided by police they were scared they weren't going to get back to their hotel in time to catch their plane."
However, she got a text from them Tuesday morning saying they had caught their flight to Florida on time.
Mrs Holmes said she didn't think the experience would deter the couple from travelling to Las Vegas after they married there five years ago.
"They go there every year for their wedding anniversary. It won't put them off. It wouldn't put me off, either, it's a wonderful place. This is just such a terrible thing to have happened."
