A former pupil killed 10 people and himself at a secondary school in Austria’s second city, Graz, on Tuesday in the worst school shooting in Austria’s modern history.

Interior Minister Gerhard Karner said six of those killed at the school were female and three were male, without giving any details of their ages. Graz Hospital later confirmed the death of a 10th person.

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

Police said they believed the 21-year-old Austrian shooter, who was found dead in a bathroom, had been operating alone when he entered the school with two guns and opened fire. His motive remained unclear.

Director General of Public Security Franz Ruf told state broadcaster ORF that victims were found outside and inside the school on various floors, adding the gunman had been armed with both a shotgun and a pistol, both found at the scene.

Chancellor Christian Stocker called the shooting a “dark day in the history of our country”.

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

Stocker travelled to Graz where, at a press conference alongside officials including Karner, he announced three days of national mourning. A minute’s silence was set for 10 a.m. (0800 GMT) on Wednesday.

Ruf also told ORF the suspect had left behind a farewell letter, both in analogue and digital form, in which he said goodbye to his parents but gave no indication of a motive, which was still being investigated.

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

The Salzburger Nachrichten newspaper said in an unconfirmed report that the suspect had opened fire on pupils in two classrooms, one of which had once been his own. It said he had 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.

Foreign leaders including German Chancellor Friedrich Merz expressed shock.

Austria has one of the most heavily armed civilian populations in Europe, with an estimated 30 firearms per 100 people, according to the Small Arms Survey, an independent research project.

Four people were killed and 22 injured when a convicted jihadist went on a shooting spree in the centre of Vienna in 2020. In November 1997, a 36-year-old mechanic shot dead six people in the town of Mauterndorf before killing himself.