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."

Sweden's worst mass shooting left at least 11 people dead, including the gunman, and at least five seriously wounded at an adult education center west of Stockholm. The gunman's motive hadn't been determined by early Wednesday as the Scandinavian nation — where gun violence at schools is very rare — reeled from an attack.

Police have confirmed that 11 people have now died following a mass shooting at an adult education school in Sweden and the number of injured is currently unclear.