Emergency crews were called shortly after 1am on Friday morning and one person was at first reported missing, only to be found a short time later.
“All four ended up in the water due to the grounding, which happened at high speed,” said emergency worker Mats Rinman to the TT news agency.
Circumstances surrounding the incident, which involved a Targa 27 motorboat, remain unclear.
“All four who were in the boat were middle aged men. But their ages differ quite a bit. Because those who died have yet to be identified and their relatives have not been notified, I don’t want to say how old they are,” said Lena Baakk of the Stockholm police to TT.
According to Per-Ove Göthberg from the police office in Näcka, a Stockholm suburb on the edge of the archipelago, both of the men who were injured managed to get themselves onto land, but were suffering from shock and extreme cold.
Both were taken to Stockholm South General Hospital for care.