After he died in her arms, Siri helped her call the Las Vegas victim's mom

As the deadliest mass shooting in modern U.S. history unfolded in Las Vegas Sunday night, hundreds of concertgoers like Heather Gooze were forced to watch strangers die right before their eyes.

Gooze held one victim in her arms as he took his final breaths. To reach his loved ones, she turned to Siri and Facebook, she told CNN.

Gooze was there to comfort 23-year-old Jordan McIldoon for hours as he died from gunshot wounds at the Route 91 Harvest music festival in Vegas, People reported. McIldoon was one of the at least 59 killed during the horrific massacre. More than 520 people were injured. The gunman, 64-year-old Stephen Paddock, killed himself after he used at least 23 firearms, including automatic weapons, to shoot into the crowd from his 32nd-floor hotel room at Mandalay Bay Resort and Casino. Read more...