Selena Gomez and Charlie Puth paid emotional musical tributes to their late friend Christina Grimmie during their concerts over the weekend (ends12Jun16).

The former The Voice finalist, 22, was signing autographs after her concert at the Plaza Live Theater in Orlando, Florida on Friday (10Jun16) when she was approached by 27-year-old gunman Kevin James Loibl.

Loibl, who was armed with two guns, shot Christina before turning the gun on himself as the star's brother Mark tackled him to the ground. The singer was rushed to the Orlando Regional Medical Center, where she was later pronounced dead.

Gomez was a longtime friend of Grimmie's, as the pop star's stepfather Brian Teefey served as the rising singer's manager after discovering her on YouTube.

A distraught Gomez carried on with her Revival World Tour in Miami, Florida on Saturday (11Jun16), but took a moment during her set to talk about her late friend.

"When she was 14, we met her and my parents and I signed her," Selena said as she fought back tears. "One thing about Christina and her family is that she holds her faith so closely to her. And I think it's not about a religion and it's not about anything or good deeds. It's just that she had faith, and I don't really understand how this really happened, but I would like to dedicate this next song to her."

Sat at a piano, Gomez then dedicated the song Transfiguration by Christian group Hillsong United, as her fans in the audience shouted out words of support.

Later, while she was singing her track Nobody, Gomez again struggled to hide her emotions, as she broke down in tears and said, "I'm sorry" to her fans. She managed to regain her composure and carried on with the set.

Meanwhile, several of Grimmie's pop star friends paid tribute to her during the New York radio station BLI's Summer Jam concert on Saturday, including Charlie Puth, who took the stage to dedicate his hit song See You Again to his late pal. The tune was originally made in tribute to tragic Fast and Furious star Paul Walker.

"I was reading the news last night and heard that my good friend Christina Grimmie was killed, and I want to dedicate this song to her tonight," he said. "I've been upset about this all day, mainly because I just never got to say what I wanted to say to her, and I feel like this song perfectly captures that."

Also during the concert, country star Rachel Platten dedicated her song Better Place to her former touring partner, while girl group Fifth Harmony led a moment of silence for the singer.