Officials in Austria say a school shooting has left at least 10 people dead in the European nation's second-largest city, Graz. The shooter is also dead.

Austria to observe three days of mourning after a 21-year-old attacker kills at least 10 people at a school in Graz.

"I think the first thing is shock, to be honest. I think you can't react the other way. I think everyone in the school is in complete shock," said 24-year-old student Helene Parr, who knows people at the BORG Dreierschützengasse school, where the mass shooting took place.

This is the first picture of the “drop out” school shooter who killed 10 people in Austria this week in one of the worst act of violence in the country’s history.Identified as Arthur A, the 21-year-old is understood to be a former pupil at the school in the southern city of Graz.

The deadliest school shooting in the nation’s recent history has prompted some gun enthusiasts to worry about the prospect of stricter ownership laws.

Eleven people injured in a school shooting in Graz, Austria, on Tuesday are still being treated but are not in life-threatening condition, officials said.

A gunman who opened fire and killed nine people before taking his own life in a school in Austria was a former student of the college, police have confirmed. Authorities said the gunman, a 21-year-old Austrian national, opened fire at the BORG school in Graz just after 10am local time.

Police in Austria were hunting for clues on Wednesday after a gunman opened fire at his former high school a day earlier, killing nine students and a teacher in a deadly spree that stunned the country.