Ten people have been killed in a school shooting in the Austrian city of Graz, in what is the deadliest gun attack in the country's recent history.

Police said the 21-year-old gunman, a former student, took his own life in a school bathroom shortly after.

The incident took place at Dreierschützengasse secondary school in the north-west of the city.

Six females and three males were killed in the attack, according to Interior Minister Gerhard Karner. A further 12 people were injured, some seriously, according to police.

Later on Tuesday, local media reported that an injured female had died in the hospital, bringing the number of victims killed to 10.

Gunman was former student

The gunman, who has not yet been named, was a former Dreierschützengasse student who didn't graduate from the school, Karner told a news conference on Tuesday afternoon.

There has been a lot of speculation about the case, Karner noted, adding it is now the job of the criminal office to investigate.

In the same conference, police said the gunman's motive was still under investigation.

Officers alsoconfirmed the gunman was not known to police before the attack.

Current information suggests the shooter legally owned the two guns used in the attack and had a firearms licence, police added.

Local media outlets have reported the suspect used a pistol and a shotgun to carry out the shooting.

He was an Austrian man from the wider Graz region who acted alone, police said.

Three days of mourning

Three days of mourning have been declared in Austria, and a nationwide minute's silence will be held on Wednesday at 10:00 local time in memory of the victims.

Flags on the Hofburg Palace in Vienna, where President Alexander Van der Bellen has his office, will fly at half mast.

The school where the attack took place will remain closed until further notice, according to Austria's Education Minister, Christoph Wiederkehr.

The Austrian Chancellor Christian Stocker said Tuesday was a "dark day in [the] history of our country" and declared the shooting a "national tragedy".

"A school is more than just a place to learn - it is a space for trust, for feeling comfortable and for having a future," he told the conference, adding this safe place had been "violated".

"In these difficult hours, being human is our strongest point," he said.

Austria's APA news agency has reported that seven of those killed were pupils.

The attack "strikes our country right at its heart", Stocker said in the immediate aftermath.

"These were young people who had their whole lives ahead of them."

Gunshots heard inside school

Police said they began an operation at 10:00 local time (09:00 BST) after gunshots were heard from inside the school.

A specialist Cobra tactical unit, which handles attacks and hostage situations, was deployed to the school, police said.

Authorities evacuated all pupils and teachers from the building. Police confirmed the school had been secured and there was no further danger posed to members of the public.

"Locally, we have seen people crying on the streets, talking to friends that have been at the school when the shooting happened, who have maybe lost a friend," said Fanny Gasser, a journalist for the Austrian daily newspaper Kronen Zeitung.

She told BBC News "everybody knows somebody" at the school because Graz - despite being the second-largest city in Austria - is "not that big".

She said the school was likely unprepared for the possibility of an attack. "We are not living in America, we are living in Austria, which seems like a very safe space."

Local mayor Elke Kahr called the incident a "terrible tragedy".

European Commission Vice-President Kaja Kallas said she was "deeply shocked" by the news. "Every child should feel safe at school and be able to learn free from fear and violence," she posted on X.

Witnesses heard gunshots

Astrid, a woman living with her husband Franz in the ground floor flat of the residential building next to the school, told the BBC she had just finished hanging out the washing when she heard gunfire.

She said: "I heard shots. Lots of them, one after the other. 'Poof... poof... poof…. poof… poof…' again and again. I went into the flat to my husband and I told him: 'Someone is shooting!'

"He thought it was maybe something else, but we heard I reckon 30 to 40 shots. Then my husband rang the police."

"We saw one pupil at the window - it looked like he was getting ready to jump out... but then he went back inside," Franz said, adding they also saw a teacher.

The pair later saw the students had "got out of the school on the ground floor, from the other side" where they "gathered on the street", Franz said.

Queues to give blood

By Tuesday afternoon, long queues had formed outside a blood donation centre in Graz.

"Today is a hard day for all of us in Graz. I'm here to [donate] my blood to help other people who need it," 25-year-old Stephanie Koenig told Reuters news agency.

"Today I'm here because I wanted to do something. I felt helpless with the news," Johanna, 30, said.

Another person standing in line told Reuters that giving blood felt like the "only way possible to help".

The incident is the deadliest mass shooting in the country's recent history.

In 2020, jihadist gunman Kujtim Fejzulai shot four people dead and wounded 23 others on a rampage through Vienna's busy nightlife district.

Meanwhile, in 2016, a gunman opened fire at a concert in the town of Nenzing, killing two people before shooting himself dead. Eleven other people were injured in the attack.