Selena Gomez performed in Miami on Saturday night, and the singer broke down into tears when she paid tribute to her late friend, Christina Grimmie.

YouTube star Grimmie, who was also a finalist on The Voice, was shot and killed after her concert in Orlando, Florida, on Friday, June 10. Grimmie was signing autographs at the Plaza Live Theater when a man, now identified as Kevin James Loibl, 27, walked up and shot her.

Gomez dedicated "Nobody" to Grimmie when she took the stage at the American Airlines Arena, and after her teary performance, she apologized to the crowd and sat down at the piano. "When she was 14, we met her – my parents and I signed her," Gomez told the audience. "And one thing about Christina and her family, is that she holds her faith so closely to her. It's not about her religion, and it's not about good deeds. It's just that she had faith. And I don't really understand how this happened, but I would like to dedicate this next song to her."

Gomez's stepfather, Brian Teefey, became Grimmie's manager after discovering the rising star on YouTube, and in 2011, Grimmie opened for Gomez on the North American leg of the "We Own the Night" tour. On Saturday morning, Gomez tweeted the below of herself and Grimmie:



In other tragic news, 50 people have now been confirmed dead after a gunman opened fire at Pulse, a popular Orlando nightclub, which is the worst mass shooting in U.S. history.

Police say the shooter, Omar Saddiqui Mateen, opened fire just after 2 a.m. EST, and after engaging in a shoot out with police, Mateen was killed after 5 a.m. An FBI source told People that the shooter spoke with a 911 operator during his attack, pledging allegiance to ISIS and mentioning the Tsarnaev brothers, who orchestrated the Boston Marathon bombings in 2013. In a speech on Sunday afternoon, President Barack Obama stated, "We know enough to say this was an act of terror and an act of hate ... The FBI is appropriately investigating this as an act of terror," he said. "We will go wherever the facts lead us ... What is clear is he was a person filled with hatred."