OREBRO, Sweden -- Despite his gunshot wounds, sustained Tuesday in Sweden's deadliest mass shooting, Salim Karim Iskef managed to video-call his fiancee to tell her he loved her one last time.

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."

A gunman who killed 11 people, including himself, at an adult education centre in central Sweden may have been a student at the school, police said on Thursday, as they described chaotic scenes after the country's deadliest mass shooting as being like an "inferno".