Sweden's worst mass shooting left at least 11 people dead, including the gunman, at an adult education center west of Stockholm as officials warned the death toll could rise. The gunman's motive, as well as the number of wounded,

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.

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."