Here's what we know about the school shooting in Austria

GRAZ, Austria — A 21-year-old former student opened fire inside his school in Austria's second-biggest city Tuesday morning, killing 10 people, in what appeared to be the deadliest attack in Austria's postwar history.

Nine students were killed — six girls and three boys aged between 14 and 17, one with Polish citizenship — as well as a teacher, police said. Another 11 people were wounded. The attacker killed himself in a bathroom at the BORG Dreierschützengasse school in Graz, officials said.

The shooting has triggered a debate about the country's gun laws, which are among the more liberal in the European Union.

Investigators said Wednesday they had not been able to draw conclusions on the motive. Here's what we know:

Nine remain in intensive care

Austrian Chancellor Christian Stocker expressed shock and sharply condemned the shooting.

''A school is more than just a place of learning," Stocker said. ''It is a space of trust, of security, of the future. The fact that this safe space was shattered by such an act of violence leaves us speechless.''

By Wednesday morning, the authority that runs hospitals in Graz said nine patients were still in intensive care. Police said the wounded people were aged between 15 and 26. Two are Romanian nationals and one is an Iranian citizen.

Gunman hadn't completed his studies

The 21-year-old Austrian man lived near Graz and was a former student at the school who hadn't completed his studies. Police said he used a shotgun and a pistol, which he owned legally. His name was not released in line with Austrian privacy rules.

Police said he lived with his mother. Investigators searching his apartment found two farewell messages, a pipe bomb that wouldn't have worked and abandoned plans for a bombing. They didn't elaborate on those findings in a post on social media Wednesday.

''He says goodbye to his parents. But no motive can be inferred from the farewell letter, and that is a matter for further investigations," Franz Ruf, the public security director at Austria's Interior Ministry, told ORF public television Tuesday night.

Officials said they're looking at whether people were targeted or shot at random.

A country in mourning

Stocker has announced three days of national mourning. The country stopped for a moment of silence Wednesday morning, marking a day since the attack.

Hundreds of people lined the central square in Graz, a city of 300,000. Some laid candles and flowers in front of city hall. Some people hugged each other as they tried to come to terms with the tragedy. Hundreds joined Austrian officials at a service Tuesday evening in the Graz cathedral.

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

Pope Leo XIV prayed for the victims and their families in the predominantly Catholic country, telling his weekly general audience in the Vatican on Wednesday that he prayed that "the Lord receive these his children into his peace.''

Gun culture in Austria

Traditionally, many people in Austria hold weapons, which they often use to go hunting in the Alpine country's vast forests. In general, it's more common to carry a weapon for that and less for self-defense.

According to the Small Arms Survey, Austria ranks 12th in the world when it comes to holding civilian firearms, with 30 firearms per 100 residents. That's far less than in the U.S. which tops the ranking with 120 firearms per 100 residents, but more than Austria's neighbor Germany, which ranked 23rd with 19 firearms per 100 residents.

In Austria, some weapons, such as rifles and shotguns that must be reloaded manually after each shot, can be purchased from the age of 18 without a permit. Gun dealers only need to check if there's no weapons ban on the buyer, and the weapon is added to the central weapons register.

Other weapons, such as repeating shotguns or semi-automatic firearms, are more difficult to acquire. Buyers need a gun ownership card and a firearms pass.

Austria Press Agency reported Wednesday that the suspect had a gun ownership card, but this document merely entitles a holder to acquire and possess, but not to carry weapons such as the handgun. That weapon also would have required a firearm pass.