The Uport Music Weekend in Ulricehamn took an unusual turn this year, as volunteers cleaning up the area after the concert one night were suddenly attacked by a homemade explosive device of the most peculiar kind.
Someone had taped a bomb onto a can of fermented herring (surströmming) on thrown it into the festival grounds.
"I thought it was petroleum gas exploding," festival director Sebastian Andersson told local paper Ulricehamns Tidning.
Andersson was in one of the dressing rooms on the festival grounds at 4am on August 2nd - when suddenly there was a bang.
"Everything shook and a window cracked. Outside there was a huge cloud of smoke and it reeked of gunpowder and fermented herring."
The bomb left a 30 centimetre crater in the ground, surrounded by splinters of the fish can. No one was injured, but Andersson said it was a close call.
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"If it had happened just a few minutes earlier, we would have all been standing outside."
Police are searching for the herring bomber, but have made little progress. The case has been classified as vandalism, and police have made an appeal for anyone with information to come forward.