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 king and queen visited the scene of the tragic event that occurred on Tuesday and Swedish flags were flown at half-mast to honor the victims.

Sweden is reeling days after the country’s deadliest mass shooting left at least 11 people dead, including the gunman, as investigators Thursday continued to look into the shooter's motive. At least five people were seriously wounded in the violence at an adult education center west of Stockholm on Tuesday.

The authorities said that at least 11 people were killed and that the suspect was believed to be among the dead.

Witnesses who survived Sweden’s worst mass shooting have described horror and panic that gripped an adult education center west of Stockholm as the gunman killed at least 10 people.

Sweden's King Carl XVI Gustaf and Queen Silvia on Wednesday visited the grounds of the education centre where 11 people were killed on Tuesday in the Nordic country's worst mass shooting. (Reporting by Johan Ahlander and Anna Ringstrom,

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.

Sweden’s worst mass shooting has left at least 11 people dead, including the gunman, at an adult education center as officials warned that the death toll could rise.