Fifteen fans were injured when part of the roof of Oslo's Sentrum Scene caved. It is still not clear if the headliner was onstage at the time, or what caused the structure collapse.

Taking to Twitter minutes after leaving the venue, Aoki wrote: "I am saddened and shocked that a piece of the roof collapsed in an accident at the venue in Oslo tonight."

None of the injuries were reported as serious. Local authorities are investigating the incident.