Off-duty security guard Aidan Becker was fatally stabbed at Mernda train station, in Melbourne's northeast, on Friday evening after rushing to the 14-year-old boy's aid.
The group of teenagers allegedly pursued Mr Becker and attacked him as he escorted the boy from the train station.
Despite the efforts of paramedics, he died at the scene.
Mr Becker has been remembered as a beloved member of the community, including by his alma mater St Josephs Primary School, Mernda.
"St Joseph's Primary School extends our deepest condolences to the family and friends of Aidan Becker, a much-loved former member of our school community," the school said in a statement on Tuesday.
"Aidan will always be remembered as part of the St Joseph's community, and our thoughts and prayers are with his loved ones during this incredibly difficult time."
It shared a written prayer for the former student, his loved ones and the school community.
Four male teens were arrested at the scene on Friday evening and have been charged with murder and armed robbery.
The eldest, Mike Pikos, 18, appeared before Melbourne Magistrates Court on Sunday and was remanded in custody to return to court on June 24.
A 16-year-old from Whittlesea, a 17-year-old from Geelong and a 17-year-old from the City of Yarra were each charged with the same offences and will appear at a children's court at a later date.
The schoolboy's family was "deeply saddened by this heartbreaking loss," it said in a statement released by Victoria Police on Tuesday.
"(Mr Becker) showed extraordinary courage and compassion in risking his life to save our son," they said.
It followed an earlier statement from Mr Becker's family, shared by friend Chris Katelaris.
"The Becker family are grieving the unimaginable loss of their son and have asked that their privacy be respected as they come to terms with this devastating tragedy," the statement read.
"The outpouring of support from the public has been deeply appreciated and the family are grateful for the kindness and compassion shown during this time."
The statement was shared to a GoFundMe page launched by Mr Katelaris to support the family, which had raised more than $71,000 on Tuesday afternoon.
The incident has left deep scars on the Mernda community, with residents turning out in droves to leave bouquets and handwritten notes near the site of Mr Becker's death.
Victorian Premier Jacinta Allan was scheduled to meet with his family on Tuesday.
"It's an opportunity for me to sit and listen," the premier said.
"And also express my deepest, deepest sympathy for someone who was a strong young man, a proud member of the local community who has been killed in the most awful, violent and tragic of circumstances."
The government's Violence Reduction Unit was working to understand what led to the incident, Ms Allan said.
Opposition police spokesman Brad Battin warned the incident was another example of Victoria's escalating "crime crisis," repeating earlier comments from Opposition Leader Jess Wilson.
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