Mayor Elke Kahr described the events as a “terrible tragedy,” the Austria Press Agency reported. It added that the fatalities were seven students and one adult.

Kahr said that many people were taken to hospitals with injuries.

Police said they believe the assailant acted alone.

Special forces were among those sent to the BORG Dreierschützengasse high school, about a kilometre from Graz’s historic centre, after a call at 10am (6pm AEST).

At 11.30am (7.30pm AEST), police wrote on social network X that the school had been evacuated and everyone had been taken to a safe meeting point.

They wrote that the situation was “secured” and there is no longer believed to be any danger.

Police deployed in large numbers, with police and other emergency vehicles guarding the area around the school and with at least one police helicopter flying above the area, according to photos published by the regional newspaper Kleine Zeitung.

Graz, Austria’s second-biggest city, is located in the southeast of the country and has about 300,000 inhabitants.

Austrian Chancellor Christian Stocker, who is going to Graz, said the shooting “is a national tragedy that deeply shocks our whole country.”

“There are no words for the pain and grief that all of us — the whole of Austria — feel now,” he wrote in a statement posted on X.

President Alexander Van der Bellen said that “this horror cannot be captured in words.”

“These were young people who had their whole lives ahead of them. A teacher who accompanied them on their way,” he said.

Interior Minister Gerhard Karner was also on his way to Graz.

“Schools are symbols for youth, hope and the future,” European Commission President Ursula von der Leyen wrote on X.

“It is hard to bear when schools become places of death and violence.”