A recent University of Arizona graduate is among the missing in the chaotic aftermath of the massacre in Las Vegas, where officials say a lone gunman opened fire on a country music festival, killing more than 50 and injuring more than 500.

Christiana Duarte, who earned her bachelor's degree in business marketing from the University of Arizona’s Eller College of Management in May, was at the concert and has not been heard from since the shooting broke out, according to her family and friends, who have been posting to social media asking for help securing information.

Her family, friends and former sorority sisters at Sigma Kappa, have been posting to social media asking for any information about Duarte. Her aunt, DeeDee White, confirmed late Monday morning via Facebook that Duarte is missing.

The University Medical Center of Southern Nevada, which accepted the bulk of the shooting victims, said Duarte is not currently at the hospital. That could mean she was treated and released, or are listed as a “Jane Doe.” Complicating the issue, Duarte reportedly lost her phone and identification before the concert began, according to the Los Angeles Times.

The missing persons hotline set up in the wake of what’s being called the deadliest mass shooting in U.S. History has been overwhelmed and temporarily shut down, according to tweets from the Las Vegas Metropolitan Police Department.

Duarte had recently started a job with the Los Angeles Kings hockey team and moved back to southern California, where she was raised.

Contact reporter Hank Stephenson at hstephenson@tucson.com or 573-4279​. On Twitter: @hankdeanlight