A gunman who killed 11 people, including himself, at an adult education centre in central Sweden may have had links to the school, police said on Thursday, as they described chaotic scenes after the country's deadliest mass shooting as being like an "inferno".

Sweden is reeling from the country's deadliest mass shooting this week as investigators continue to look into the gunman's motive.

Swedish police confirm around 10 people were killed at a school for adults on the outskirts of Stockholm. The gunman is believed to be among the dead.