ISTANBUL / GENEVA

A non-functional pipe bomb was found in a house search at the residence of the 22-year-old behind a deadly shooting at his former school in the Austrian city of Graz, police said on Wednesday.

According to the Styrian State Police Directorate, the improvised explosive device was found on Tuesday, shortly after the attacker fatally shot himself following the incident, the Austrian Press Agency reported.

Authorities also recovered a farewell video he had sent to his mother, along with a suicide note.

Police spokesperson Sabri Yorgun said the suspect had legally obtained both the shotgun and the pistol used in the attack, but added: "He should not have been carrying them under any circumstances."

While some media outlets suggested the perpetrator may have been a victim of bullying, the police declined to confirm this, and further details about his time at the school remain unclear.

Separately, since the attack Austrian authorities have reported a series of threats apparently inspired by it. Franz Ruf, director general for public security, told public broadcaster O1 on Wednesday morning that "several copycat offenders" had made threats in the wake of the shooting.

The Styrian police confirmed that investigations are underway but refrained from describing the suspects as copycats.

"There has been no further shooting spree, but there are suspects who are now seizing on the fact that such an incident occurred," said Yorgun.

According to police, Tuesday's school shooting claimed the lives of nine students age 14-17, including six girls and three boys. All but one student – a Polish national – were Austrian.

A teacher who was hospitalized with serious injuries also died.

Eleven other people, aged 15-26, were injured, including eight Austrians, two Romanians, and one Iranian, the police said, adding that all of the injured are now out of danger.

Three days of national mourning have been declared starting Wednesday morning.