The man was lying at a gate to an apartment building in Solberga and was found by passers-by who alerted SOS Alarm. According to police, the man was stabbed with a sharp object.
"We are investigating what happened. The crime scene may be in the stairwell or laundry room, says police spokesman Towe Hägg.
At 19 p.m., the police announced that the man died from his injuries, and that one person had been arrested on suspicion of murder.
The police requested a train stop at Älvsjö station until "certain investigative measures have been carried out", they write on their website.
"This is because we need to see if there is anyone at the station that we might need to talk to, so that they don't jump on the commuter train," says Towe Hägg.
Just before 17 pm, the trains could again stop at Älvsjö.