'I don't understand how this happened': Selena Gomez breaks down in tears as she pays tribute to Christina Grimmie during Miami concert

Selena Gomez is mourning the loss of her close friend Christina Grimmie, who was tragically shot dead as she signed autographs for fans at her Florida concert on Friday night.

And Selena delivered a moving tribute to the 22-year-old Voice star as she performed in Miami on Saturday, after cancelling a meet and greet over security fears.

The 23-year-old broke down in tears as she spoke about her relationship with Christina before performing Hillsong Worship's Transfiguration in her honour.

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Emotional: Selena Gomez delivered a moving tribute to Christina Grimmie during her Miami concert on Saturday night, and dedicated a performance of Hillsong Worship's Transfiguration to her

'When she was 14, we met her and my parents and I signed her,' Selena said as her voice cracked with emotion.

'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.'

She added: '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.'

Selena, who was sitting at a piano for her performance, then wiped away tears as the crowd voiced their support, before launching into the song.

Selena also started crying while performing the song Nobody, and mouthed the words 'I'm sorry' to the audience.

The actress and singer had shared a photo with Christina to Twitter on Saturday after hearing about her devastating death, along with the words: 'My heart is absolutely broken. I miss you Christina.'

Selena decided to go ahead with her performance at Miami's American Airlines Arena that evening, but cancelled a meet and great with fans due to security concerns. 

Christina's killer Kevin James Lobil, 27, drove from his home in St Petersburg to the gig in Orlando armed with two handguns and a knife before opening fire during her meet and greet. 

The star's brother Mark tackled the deranged fan after he shot Christina in the head, preventing him from injuring anyone else. The gunman then shot himself dead. 

There are no metal detectors at the venue, but unarmed security guards are employed to check people's bags. 

'My heart is absolutely broken': The pop star - who went ahead with her concert but cancelled a meet-and-greet over security concerns - had earlier shared this photo after learning of Christina's tragic death

Close: The 23-year-old was very good friends with Christina, who served as her opening act several times. They are pictured together here in 2010

USA Today has since reported that Orlando's Plaza Live Theater, where the shooting happened, has suspended all events until further notice.

Selena's stepfather Brian Teefey was Christina's manager, and set up a GoFundMe page for her family which has already raised almost $77,000. 

He wrote on the fundraising page: 'Words cannot begin to describe the pain I am feeling. I learned this business through the eyes of a father and Christina was like a second daughter to me.

'Christina was like a second daughter to me': Selena's stepfather Brian Teefey was Christina's manager and set up a GoFundMe page to help her family, which has already raised almost $77,000

Gone too soon: The 22-year-old singer was shot while signing autographs for fans at her Orlando concert on Friday night. She is pictured here in May 

'All I wanted to do was assist her in achieving her musical dreams while protecting her from the pitfalls associated with the business. I never could have imagined this horrific event being one of the pitfalls needing to be avoided.'

Teefey added: 'In Christina’s honor I have created a Go Fund Me page to assist her family in their time of need. As family Mother, Father, and Brother made the ultimate family sacrifice to support Christina on her musical journey.

'They did nothing but love her and support her as family the best they knew how, the only worry I want them to have at this point is that of recovery. Grimms I love you, and miss you beyond comprehension.'

Family: Selena is pictured here with her stepfather Brian and mother Mandy Cornett in 2008