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.

A 10th victim has died after a 21-year-old former student opened fire in a secondary school in Graz before killing himself.

Ten people were killed in a mass shooting at a high school in Graz, the country’s second-largest city, the police said. The gunman also died, in an apparent suicide.

Austria ranks among the highest in Europe for civilian gun ownership, with approximately 30 guns per 100 residents, according to the 2017 Small Arms Survey, a Geneva research group. While countries such as Cyprus, Finland, and Iceland report slightly higher rates, Austria remains an outlier in the continent.

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.

A former student killed 10 people and then himself in a shooting in Graz on Tuesday, the police said. The authorities said a pipe bomb and a “farewell letter” were found at the shooter’s house.

Police have revealed chilling details about what they found in the home of a former student, 21, who is suspected of leaving a farewell message for his mom before killing 10 in the school shooting in Graz,

Students were sitting in their classrooms at a secondary school in Graz when a 21-year-old Austrian man shot dead nine people, before killing himself.Twelve people were injured in Tuesday morning's violence,