A 10-year-old boy from Hailuoto died from injuries sustained while playing, said the Oulu police.
Two five-grade schoolboys on Friday remained behind to play in a nearby playground after the school day came to an end.
One of the boys was accidentally strangled while playing on a swing.
The boy was ferried to Oulu University Hospital but died from his injuries.
The incident is being treated as an accident. It does not involve other people and neither is it a case of crime.