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.

Austria came to a standstill on Wednesday to mourn victims of one of the worst outbreaks of violence in its modern history, as authorities search for clues to why a 21-year-old gunman shot dead 10 people at his former high school before killing himself.

A school shooting in Austria left at least nine people dead and dozens more injured, authorities said, in one of the worst such incidents in the country’s history.The death toll from the shooting, which took place on Tuesday morning in Austria’s second biggest city of Graz,