A gunman opened fire at an adult education center in the Swedish city of Örebro on Tuesday, killing at least 10 people in what the country’s prime minister called the “worst mass shooting in Swedish history.

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.

Swedish Prime Minister Ulf Kristersson described Tuesday’s shooting at an adult education center in Örebro (200 kilometers west of Stockholm), which left at least ten people dead, as the “worst” in the history of the Nordic country.

As many as 10 people have died in a shooting at a school in Sweden, police have confirmed. The deadly attack happened on Tuesday afternoon at Risbergska School, an adult education centre, in the city of Örebro, about 125 miles west of Stockholm.

About 10 people including the gunman have been killed at an adult education center in what Sweden’s prime minister called the country’s “worst mass shooting.”

Sweden’s worst mass shooting has left at least 11 people dead including the gunman and five seriously wounded at an adult education center

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,

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."