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".

OREBRO, Sweden (Reuters) - Swedish police found three rifles in the adult education centre in Orebro where a gunman killed 11 people and wounded several others this week in the country's deadliest mass shooting, a spokesperson said on Thursday.

While the police say they have not yet identified a motive for Sweden’s worst mass shooting, Reham is alarmed that the man police believe to be the perpetrator attacked a school where Swedish for Immigrants (SFI) courses are taught.

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.

Swedish police are investigating the potential motives of an attacker who killed 11 people, including himself, in a mass shooting at an adult education center in the town of Orebro.

The attack on Tuesday - described by Sweden's prime minister as the "worst mass shooting" in the country's history - happened at a school for adults.

Salim Iskef, 29, fled the Islamic State and Syria to form a better, more secure life in Sweden, only to be gunned down this week in the worst mass-shooting in Swedish history.

Swedish police said the gunman in the country’s worst mass shooting was connected to the adult education center where he opened fire Tuesday, killing 10 other people. Police later found him dead.

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.

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