Ten people have reportedly lost their lives and dozens more have been injured after a former pupil opened fire on an Austrian school, in what was described as one of the worst mass killings in the country’s history.

Special forces police descended on the BORG High School in the city of Graz shortly before 10 am local time on Tuesday after reports of gunshots arose.

The suspect is among the dead after having killed himself in the toilet after opening fire on two classrooms and shooting in circles.

He has been described by local media as a 22-year-old former student who had been a victim of bullying at the school. In the chilling video that emerged online, the sound of gunshots rang outside the campus, while others showed bodies lined up on stretchers.

Pupils were also seen running for their lives from the school as heavily armed cops scour the corridors. Several students and at least one adult were among the dead, as shared by the mayor.

At least 28 people were wounded in the incident, with four of them said to be in critical condition.