The Babel club in Malmo, Sweden, had its entire entrance blown apart in the early hours of Friday morning.
A witness tweeted: "Nightclub has just been bombed in Swedish city of Malmö. Several loud explosions heard on the scene."
Cops and a bomb squad descended on the scene with the area placed on lockdown for hours.
Another bystander said: "I was awakened by a big crowd. It was a terrible bang."