A 17-year-old girl, a 17-year-old boy and a 46-year-old man fell victim to the perpetrator's bullets at the mall in Denmark July 3.

The shooting took place on a Sunday afternoon before artist Harry Styles was due to perform at the nearby Royal Arena. Many people were on the move at the mall and several Swedes were injured in the attack.

"This is a particularly serious case that the police have investigated very carefully," special prosecutor Søren Harbo of the Copenhagen police said in a press release.

The 23-year-old was arrested shortly after the shootings and has been in custody ever since.

The trial begins in Copenhagen on June 12 and is expected to last six days.

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Police have cordoned off the area – see the pictures in the clip. Photo: Mathias Øgendal