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".

Police say 5 people have been shot at a school in the Swedish city of Orebro, but they have not provided any information on the victims' conditions.

Police remained on the scene of an adult education center in Orebro, Sweden, where a deadly shooting left around 10 people dead on Tuesday, Feb. 4.

"But this hate, it is coming from somewhere." A member of Kasselia's congregation, 29-year-old Salim Iskef, was among those murdered in Orebro on Tuesday in Sweden's first school shooting and the worst mass shooting in the country's history.

A 28-year old man who fled the war in Syria was among the victims of a school shooting in Sweden earlier this week.

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.