One day after the killings at an adult educational center, some gathered to lay flowers and come to grips with the violence.

The suspected gunman, who was among the dead, was named in media reports as Rickard Andersson, 35, a former student of the school who lived locally.

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

The police responding to the attack encountered firing so intense that they struggled to tell how many gunmen were on the scene, an official said.

Officials in Sweden have vowed to determine why a man killed 10 people, and apparently himself, in an unprecedented attack that's shaken their "society to its core."

Andersson was said to be a recluse who had maintained little contact with his family for years before tragedy unfolded at Risbergska School in Orebro

The suspected gunman in a deadly school shooting in Sweden shot himself after killing 10 people on Tuesday, police believe. Armed police exchanged fire with an unnamed shooter at Risbergska School in Örebro,