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

Shooter responsible for Sweden's deadliest mass shooting earlier this week was linked to the adult education center where he opened fire, using at least one rifle-like weapon, according to law enforcement officials on Thursday.

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."