Victoria Police homicide squad detectives are investigating after a 63-year-old man died in hospital on Thursday.
Six days earlier, he was allegedly assaulted metres from Strathaird Primary School at Narre Warren South, in Melbourne's outer southeast.
On Friday afternoon, two bouquets of flowers sat near the scene of the attack.
Children ran across the nearby oval and families moved through the reserve as the school day wound down.
Grandmother Jackie Mashiter said she was shocked the alleged assault happened so close to a primary school.
"It's an absolute disgrace, especially outside of a primary school," she told AAP outside the school gates.
"Parents and kids should be able to feel safe coming to school."
Ms Mashiter said she had passed the reserve shortly after the incident while collecting her granddaughter from school.
She said she saw a man on the ground surrounded by several people but did not initially realise the gravity of what had happened.
"I just saw him laying down and I thought he was actually just resting and waiting for his kids to come out," she said.
After learning of the man's death, she said her thoughts were with his family.
"I'm just so sorry for the family that it's happened to," she said.
"I couldn't imagine what they're going through."
Police believe the man was first assaulted at the reserve near the school about 3.15pm on June 12, shortly before students were due to leave for the day.
Two men aged 21 and 22 have been charged with recklessly causing serious injury.
The charges were laid before the victim died.
Homicide detectives would consider alternate charges following the results of a post mortem examination, police said.
A number of parents and students witnessed the incident and its aftermath.
A father, who asked not to be named, said his priority was making sure his son was safe and did not become a witness.
"I shielded my son straight away, I didn't want him to see anything," he said.
The reserve sits metres from the school grounds and a children's centre and is regularly used by families, dog walkers and local residents.
On Thursday, the school's principal Julie Kennedy advised parents and carers the alleged victim had died in a message seen by AAP.
"It is with great sadness that I inform you the victim of the alleged assault… has passed away," she wrote.
Ms Kennedy advised parents that wellbeing supports were available for students and urged anyone with information to contact Victoria Police.
Education Minister Ben Carroll said his sympathies were with the local community and psychologists and education support staff had been arranged for affected students and carers.
"What's occurred here is a complete tragedy, and to think that was witnessed by young children makes the tragedy even … worse," he told reporters.
The Department of Education was aware of the distressing incident with support offered to those affected.
"The safety and wellbeing of students and staff is always our priority," a spokesperson said.
The two alleged attackers remain in custody and are expected to return to court in July.
Police believe the parties involved were known to each other.
10°C