The first photographs of the Austrian school shooter who killed 10 students at his former school in Graz on Tuesday have emerged.

The images of gunman Artur A surfaced following the horrific attack at BORG Dreierschutzengasse high school, where he opened fire with a shotgun and pistol before taking his own life.

The "bullied" dropout had sent his mother a farewell video moments before launching his assault, but she only opened the message 24 minutes after receiving it - too late to prevent the tragedy.

By the time she alerted police, her son had already stormed into two classrooms.

Newly-named gunman Artur A was 'inconspicuous' and 'completely withdrawn', neighbours said

Investigators discovered the farewell message when searching the shooter's home on Tuesday night.

Franz Ruf, public security director at Austria's Interior Ministry, told ORF public television that a "farewell letter" had also been found.

"He says goodbye to his parents. But no motive can be inferred from the farewell letter, and that is a matter for further investigations," Ruf said.

According to Austrian news outlet Heute, the shooter's mother immediately notified police after she saw her son's message.

The gunman lived with his single mother in a low-income housing estate on the outskirts of Graz, according to Krone Zeitung.

PICTURED: Police officers walk towards the flat of suspect Artur A following his deadly shooting

PICTURED: Paramedics standing in front of the school after the attack unfolded

Neighbours described him as "inconspicuous" and "completely withdrawn".

"He wore his large headphones and a backpack whenever he went in and out. He never said hello, but he was never unpleasant in any way," one neighbour told Profil news outlet.

His mother has been widely described as a "kind" and "truly sweet" woman.

"I'm praying not only for the victims' families, but also for the mother," another neighbour said.

PICTURED: People light candles in Graz's main square after the deadly shooting

Police confirmed the killer had legally owned both weapons, with reports suggesting he had purchased one of the guns just days before the attack.

In the wake of the shooting, Austria has been plunged into a state of shock - its Chancellor Christian Stocker has declared a "dark day in the history of our country" and has announced three days of national mourning.

The first victim to be identified was 15-year-old Kosovan girl called Lea.

Her aunt wrote on Facebook: "Today, my niece Lea tragically lost her life in the attack in Graz. We pray for her soul and express our gratitude to all those who share our pain during these difficult times."