At 18.59 on Monday, the Stockholm police received an alarm about a fight.
When the police arrived at the City Terminal, they met an injured person, a man in his 45s.
He was taken to hospital by ambulance.
The damage situation is still unclear.
The suspected perpetrator, who is in his 50s, has been detained on suspicion of attempted murder.
The police have cordoned off the crime scene and are working during the evening to gather information.
- We have blocked off and are on site to find out as much as possible, if there are people at the City Terminal who may have heard or seen something that can help the investigation staff, says Towe Hägg, Police Press Service.