Danish police said several people had been hit by gunshots at a shopping centre in the capital Copenhagen on Sunday, and one person had been arrested.
Copenhagen police tweeted that officers had been sent to the Field's mall after reports of a shooting.
They advised people inside the centre to stay put and await police assistance.
Local media published images showing heavily armed police officers at the scene, as well as people running out of the mall.
Police did not immediately give any details about the condition of those who were shot.
British singer Harry Styles was due to perform later in the evening, at 8 p.m. local time, at a concert venue less than a mile from the mall. The concert promoter Live Nation could not immediately be reached for comment.
More to come.