A 21-year-old gunman who killed nine students and a teacher at his former school in Austria had developed a fascination and "significant passion" for such shootings in recent years, investigators say.

The 21-year-old, who meticulously planned the attack at his former high school in Graz, killed nine students and a teacher.

Investigators say a former student who killed nine students and a teacher in Austria a week ago and then took his own life ...