The police were alerted at 00.17 that a man had been found outside on the ground at a multi-family home in Vårby.
– We understood on the spot that he had fallen from an apartment. Since there are unclear circumstances, the criminal classification will be attempted murder, says Per Fahlström, press spokesperson at the police in Stockholm.
Two men who were in the apartment, and two men in the stairwell, were arrested.
The home is cordoned off for technical inspection.