Twin Sisters Wounded in Las Vegas Recall How They Survived

Identical twins Natalia and Gianna Baca were both struck by gunfire in Las Vegas Sunday night, where an off-duty firefighter who was attending the festival saved one sister's life.

The 17-year-olds were singing along to Jason Aldean's closing concert when they heard what they thought were fireworks sounding off around them, they told ABC News Tuesday.

"Someone behind me said that it wasn't a gunfire," Gianna said. "So we all stood up and it happened again and people just fell on top of each other, people screaming, there was blood everywhere and that's when I felt like a pain in my hip and it felt like a boulder hit my hip."

Her boyfriend helped her off the ground but they lost sight of her sister Natalia in the shuffle.

Meanwhile, Natalia was attempting to cover herself in the open lawn while sitting with a friend, Riley.

"We were just holding our heads, just praying and holding hands and then I got hit," Natalia said. Riley took off his shirt and started applying pressure to the wound on her shoulder. He pulled her up and ran to a nearby triage tent for help.

As Riley and Natalia arrived in the tent, Dean McAuley, an off-duty firefighter from Washington, ran over to help assess her wound while she began to go into shock.

"Dean was an amazing guy. He stuck with me the whole night and I just give him full props for actually saving my life," she said.

"He could have not acknowledged me in that tent, he was just a volunteer that was taking his time out of that night and saving people's lives and he didn't have to but he is a very strong man and his family should be very proud of what he's doing," Natalia added.

McAuley recorded a message to Natalia for Good Morning America, telling her, "I am very proud of you, and your strength and your ability to stay calm. You were a very bright moment for me last night. I hope someday we can reconnect and I can give you a big hug."

Doctors told ABC News that after the bullet struck Natalia's shoulder, it shattered inside her body. She is in stable condition with a tube draining blood from her rib cage, but the bullet punctured her lung and she will likely require surgery.

Sister Gianna was shot in her behind and the bullet went through her body, leaving near her hip. She was released from hospital care on Monday morning.

"I feel like everyone should be impacted on this and be thankful that we have lives and just keep believing you never know what's going to happen to you," Natalia said.