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 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.

The suspect in the violent Austria school shooting had failed to pass the test for military service and was a fan of online first-person shooting games

A shooter opened fire at a high school in the Austrian city of Graz on Tuesday, killing 10 people, including teenagers, in one of the worst rampages in the country’s history.