At 18.20 on Friday evening, the police received an assault alarm from Hamnpiren in Jönköping due to a riot.
Shortly afterwards, the police fired a warning shot when one of the suspects acted threateningly when the police arrived at the scene.
No one should have been injured during the intervention.
The suspect, in his 20s, was arrested at the scene on suspicion of threatening an official.
After a new assessment at the police station, the man was later detained and taken for questioning.
The police are looking for clues at the scene that can take the investigation forward and they are also looking for witness information about the riot.
The police will now make a routine report on the patrol's actions during the intervention.