Two people are dead after one fell off a seven-story staircase and crushed the other during an Abba tribute concert in Uppsala, Sweden, on Tuesday night. About a thousand Abba fans had gathered for the show at Uppsala Konsert & Kongress, near the band’s hometown of Stockholm. Half an hour before it began, however, the person fell from the staircase into the foyer, killing one and severely injuring another. The injured person was hospitalized and is expected to recover. It’s unclear what caused the fall, and authorities have not identified either victim. The concert was canceled and the hall closed for cleanup and witness interviews. MTLive, which put on the show, wrote on Facebook, “Unfortunately, we have to announce that a terrible event has happened. What we know is that someone jumped or fell high in the arena and hit other people. Right now we don’t know much more, everyone is in shock.” Abba is set to release a reunion album with new music this week.