Karner said another dozen people had been injured but gave no further details about the victims. Austrian media said most were students.

“There are no words for the pain and grief that we all — all of Austria — are feeling right now.”

More than 300 police were called in after shots were heard around 10am at the school, for pupils of 15 and above. Ambulances also arrived within minutes as the premises were cordoned off.

Members of the community are mourning the victims of the shooting, leaving flowers at the scene. Source: Getty / Matej Povse

The Salzburger Nachrichten newspaper said in an unconfirmed report that the suspect, armed with a pistol and a shotgun, had opened fire on pupils in two classrooms, one of which had once been his own. It said he had reportedly been a victim of bullying.

Julia Ebner, an extremism expert at the Institute for Strategic Dialogue think-tank, said the incident appeared to be the worst school shooting in Austria’s post-war history.