Austrian school shooter planned attack but motive still unclear, officials say

Flowers and candles are laid outside a school where nine students and a teacher were killed in a shooting (Darko Bandic/AP)

A man who killed nine students and a teacher at his former school in Austria and then took his own life planned the attack in detail, investigators have revealed.

However, he appears to have shot his victims at random, and investigators have still not been able to ascertain his motive.