A primary school has contacted parents to offer support after hundreds of children witnessed an alleged fatal attack on a father during afternoon pick-up.

The 63-year-old was allegedly assaulted at a reserve behind Strathaird Primary School in Narre Warren South, south-east Melbourne, at 3.15pm last Friday.

The man's son attends the school and reportedly witnessed two men allegedly beat his father with fists and a pole or metal torch. 

All three men are understood to have known each other.

The 63-year-old was taken to hospital before he died on Thursday.

Families of the 760 students at Strathaird Primary School received a letter from leadership on Monday offering support, which was published by the Herald Sun.

'You may be aware of an alleged assault that occurred in Strathaird Reserve next to our school last Friday afternoon,' it read.

'If your child witnessed the incident and you feel they need wellbeing support, please reach out to me... or the Assistant Principals and we will arrange it.'

Two men, a 21-year-old of no fixed address and a 22-year-old from Narre Warren South, were charged last week with recklessly causing serious injury.

They remain in custody and are expected to return to court in July.

One parent told the Herald Sun that many of the school children had witnessed the alleged assault.

'The kids were shaken up... They were terrified. I could see him lying on the ground and he couldn't get up. He appeared to be knocked out,' she said. 

'I believe his child was there when it happened.'

The parent said she also saw the incident and that some people shouted at the alleged attackers to stop. 

'There were two men standing over him. They were yelling at him and hurting him with a pole or a metal torch. There were people yelling at them to stop,' she said.

'It was quite quick, then they jumped in their car and drove off. This should never have happened at a school.'

A Department of Education spokesperson told AAP on Friday they were aware of a distressing incident that occurred near the school last week.

'Our immediate focus is on supporting the school community. The safety and wellbeing of students and staff is always our priority,' the spokesperson said.

'Those who witnessed the incident have been offered wellbeing support and the school is working closely with families.'

There was no visible police presence near Strathaird Primary School last week, and no signs of the incident at the scene, including flowers or tributes.

The reserve, just metres from the school, is lined with trees and features a large oval popular with dog walkers and bordered by homes overlooking the park. 

It also sits close to a children's centre.

Locals told AAP a week after the attack they knew little about what happened, with one saying, 'it's Narre Warren'.