The alarm about the incident came in just before nine o'clock on Wednesday night.
Police and an ambulance were sent to a restaurant on Storgatan where a man in his 50s had been chopped or cut by one or more perpetrators.
The man was taken to hospital by ambulance, and the injury situation is currently unknown.
- We have police on site and the restaurant premises and the area around it are cordoned off, says Rickard Lundqvist, spokesperson for the police.
No one has been arrested in the case, which is classified as attempted murder.