GRAZ, Austria (AP) — Austria fell silent for a minute on Wednesday and people laid candles in the city of Graz in memory of the 10 people killed in a school shooting that shocked the country.

Investigators said they found a farewell letter and video, a non-functional pipe bomb and abandoned plans for a bombing in a search of the assailant’s home near Graz. But they said they don’t yet know what his motive was.

Nine students were killed — six girls and three boys aged between 14 and 17, one of whom had Polish citizenship — as well as a teacher, police said. Another 11 people were wounded. The attacker took his own life.

Austria has declared three days of national mourning following what appears to be the deadliest attack in its post-World War II history. At 10 a.m. on Wednesday, marking the moment a day earlier when police were alerted to shots at the BORG Dreierschützengasse high school, the country stopped for a minute of silence.

Hundreds of people lined the central square in Graz, Austria’s second-biggest city. Some laid more candles and flowers in front of the city hall, adding to a growing memorial to the victims. The first candles were laid on Tuesday evening as a crowd gathered on the square, some people hugging each other as they tried to come to terms with the tragedy. Hundreds of people joined Austrian officials at a service Tuesday evening in the Graz cathedral.

Among those on the square Wednesday was Chiara Komlenic, a 28-year-old art history student who finished her exams at the school there.

“I always felt very protected there. The teachers were also very supportive,” she said. “I made lifelong friendships there. It just hurts to see that young girls and boys will never come back, that they experienced the worst day of their lives where I had the best time of my life. I still know a few teachers, it just hurts a lot.”

In the capital, Vienna, the local transport authority had trams, subway trains and buses stop for a minute.

The 21-year-old Austrian man lived near Graz and was a former student at the school who hadn’t completed his studies. Police have said that he used two weapons, a shotgun and a pistol, which he owned legally.

Police said the attacker lived with his mother near Graz and investigators found the two farewell messages, a pipe bomb that wouldn’t have worked and abandoned plans for a bombing when they searched his apartment. They didn’t elaborate on those findings in a post on social network X Wednesday, other than to say they haven’t yet been able to draw conclusions.

“A farewell letter in analog and digital form was found,” Franz Ruf, the public security director at Austria’s Interior Ministry, told ORF public television Tuesday night. “He says goodbye to his parents. But no motive can be inferred from the farewell letter, and that is a matter for further investigations.”

Asked whether the assailant had attacked victims randomly or targeted them specifically, Ruf said that is also under investigation and he didn’t want to speculate.

He said that wounded people were found on various levels of the school and, in one case, in front of the building.

By Wednesday morning, the authority that runs hospitals in Graz said that all patients were in stable condition. Nine were still in intensive care units, with one needing a further operation on a facial wound and a second on a knee injury, while another two had been moved to regular wards.

Police said none of their lives were in danger and that the wounded people were aged between 15 and 26. Two are Romanian nationals and one is an Iranian citizen.

“Graz is the second-largest city in Austria, but we still say that Graz is a village,” said Fabian Enzi, a university student among those on the main square of the city of about 300,000 people Wednesday.

“Every time you are out you meet people you know. There is a high chance that with such an attack you know people which are affected,” the 22-year-old said. “There are a lot of desperate faces.”

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Geir Moulson in Berlin contributed to this report.