Swedish police say the shooter who killed 10 people in the country’s worst mass shooting was connected to the adult education center where he opened fire with at least one rifle-like weapon.

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."

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.