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.

Residents of Graz gathered for a mass and a candle lit vigil to mourn the 11 victims who were killed after a former pupil opened fire in a school. View on euronews

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 debate about gun laws in Austria is gathering pace after a 21-year-old former student killed 10 in a shooting at a school in Graz on Tuesday. View on euronews

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.