Photo: The Canadian Press

Some survivors of the Las Vegas mass shooting said they were ready for closure, though they confessed feeling engulfed by anxiety and security fears while gathering in a large group for the first time since the attack.

Theresa Almada, 49, drove Thursday evening from San Diego back to Las Vegas to attend a country music concert benefiting victims of the deadliest mass shooting in modern U.S. history.

Fifty-eight people were killed and hundreds more were wounded Oct. 1 at the Route 91 Harvest Festival on the Las Vegas Strip. Gunman Stephen Paddock opened fire from the 32nd floor of the Mandalay Bay casino-hotel tower, unleashing more than 1,000 bullets into the crowd.

Almada was physically unharmed and was able to run back to her hotel, but she said she feels immense anxiety that comes in waves. She gathered at the Thursday night benefit concert with fellow survivors wearing matching orange t-shirts and bracelets. Almada said she hopes she'll feel some sense of closure and can begin to heal from the traumatic experience.

"I don't know if there's a copy-cat person out there, but I'm not going to let him do what he did to every single day of my life," Almada said of Paddock.

Susan Pudiwitr, 56, of Las Vegas, who suffered a bullet graze wound on her hip, said she finds comfort being among other survivors but being in a big crowd again makes her think about who's out there, where they are and how she would save herself and her friends if the worst happened again.

"It's been hard. I don't sleep. I have trouble eating," Pudiwitr said.

Security was also on the mind of John Rich of the American country music duo Big & Rich, which headlined the benefit concert along with Rascal Flatts. Thursday's concert at the indoor Orleans Arena was expected to attract 8,000 people, including 2,000 police and other emergency workers.