A wounded woman is moved outside the Tropicana casino in Las Vegas on Oct. 1, 2017. (Chase Stevens/Las Vegas Review-Journal via AP)

On Sunday night, a gunman on the 32nd floor of the Mandalay Bay Resort and Casino in Las Vegas opened fire at an outdoor concert, leaving at least 59 people dead and injuring over 500 others in the worst mass shooting in U.S. history.

One of those killed was Jennifer Topaz Irvine, a San Diego-based solo practitioner and a graduate of California Western School of Law. According to local news reports, Irvine, 42, had been watching singer Jason Aldean’s performance at the Route 91 Harvest Festival, a three-day country music event, when she was killed.

Jennifer Topaz Irvine

In a Facebook post, Kyle Kraska, a sports director for CBS News 8 in San Diego and a friend of Irvine’s, stated that Irvine had been “holding hands with her girlfriends singing and dancing to country music when she was shot in the head.”

Records on file with The State Bar of California show that Irvine was admitted to practice law in 2005. That same year she took a position at what was then known as Lerach Coughlin Stoia Geller Rudman & Robbins, according to her profile on professional networking website LinkedIn. (Lerach Coughlin, a giant of the plaintiffs bar, subsequently changed its name to Robbins Geller Rudman & Dowd.)

Nearly two years later, Irvine became manager and owner of Would Corp., an investment property management and development group, before opening her own solo family law and criminal defense practice in 2011.

Local police and FBI officials are still attempting to piece together the means and the motive behind the mayhem Sunday night in Sin City. Law enforcement authorities have identified Stephen Paddock, a 64-year-old from Mesquite, Nevada, as the shooter and found at least 23 firearms, including a handgun, in his hotel room.

One person caught up in the horror was Brian Claypool, a solo practitioner from Pasadena, California. In an interview with ABC News, Claypool said that he was sitting in the VIP area of the concert near the stage when he heard gunshots.

“I knew something was wrong and then I heard shots fired, just going off like they were right on top of us,” Claypool told ABC News. He managed to escape the barrage of gunfire but said that the images of that evening will live with him forever.

William Ciancaglini, a Philadelphia lawyer, also spoke with The Philadelphia Inquirer about fleeing the area near the Mandalay Bay after Paddock opened fire on those below.

Meanwhile, an in-house lawyer at CBS Corp. was fired this week after making insensitive remarks on social media about victims of the massacre in Las Vegas.