“The person who called the police had spoken to several neighbours in the house who also thought it smelled like gas, and were worried,” said Stockholm fire fighter Björn Hörnsten to the national radio station SR.

On the scene, however, emergency services were quickly able to classify the unpleasant smell as harmless, since it didn’t come from anything more dramatic than a traditional Swedish autumn party.

“I guess somebody didn’t know what surströmming smells like,” said Sven-Erik Olsson from the police’s command centre to the TT news agency.

Surströmming, or fermented herring, is a traditional Swedish delicacy, but its odour is notoriously foul. In the beginning of fall, it’s not uncommon for Swedes to gather some friends and spend an evening together enjoying the smelly fish at what is called a surströmmingsskiva (fermented herring party).

But on this occasion, the smell spread from the apartment out to the stairwell, scaring the neighbours.

“They’ve got gas in the building, so I find it a bit strange that they called us. They ought to know what it smells like when you turn on a gas stove. It doesn’t smell like surströmming at all,” said Hörnsten.

According to the Stockholm fire department, this isn’t the first time they’ve rushed out to respond to an emergency call and ended up at a surströmming party.