"My son said one of the boys asked them for assistance, but should you need to ask?" she told the Herald.
"[Her son] was kicked and spat on and one boy was punched in the face."
She was waiting for her son at Papakura station when he rushed to the family's car and asked her to drive off quickly, before he would tell her what had happened.
In another incident, Auckland Transport called the police to Manurewa station on Wednesday evening after CCTV monitoring caught footage of an incident between two males on the platform, one of whom appeared to have a firearm or replica.
The callout followed the removal of a male from a train at the station, a spokesman said.
A police spokeswoman confirmed that officers responded to a report of a male there "with some type of firearm", but said he had left by the time they arrived at the station, although they were able to speak to the other person involved.
Contrary to Auckland Transport's initial belief, she said it was "not our understanding" that the two incidents were linked.
But Auckland Council members Calum Penrose and George Wood say they are dismayed at continuing violence on the city's rail network, and want the transport body to make it safer for more people to use the new electric trains.
"Safety is absolutely paramount on our trains if we're having a big push to public transport. And Auckland Transport have, in my view, dropped the ball," said Mr Penrose, who holds the council's crime prevention portfolio.
"If these scumbags continue to use our public transport and intimidate those who are more vulnerable, people will say, 'Stuff it, I'm going to take my car to work - it's safer'."
He acknowledged a "slight improvement" after Auckland Transport allocated $5 million to beefing up security in April, in response to a series of attacks on rail staff, but said the situation appeared to be deteriorating again.
The reluctance of security guards to intervene in the Puhinui incident reinforced a need for a special police force to improve safety on trains.
Mr Wood said he was still waiting for a report from the police on their investigation into a mini-riot at Britomart station after Christmas in the Park on December 13 and an attack on a train by stone-throwing youths at Glen Innes later that night.
The Auckland Transport spokesman would not comment on the alleged inaction by the security guards, saying only that the Puhinui incident was in police hands.
Inspector Bronwyn Marshall of the Counties Manukau police said the Puhinui incident had been assigned to an investigator, and CCTV footage would be sought from Auckland Transport.
She said police were continuing to work with that body, Auckland Council and partner agencies to address any security and safety issues on trains and at stations.
Trouble on tracks
• February 12 - schoolboys attacked at Puhinui station.
• February 18 - incident between two males at Manurewa station in which one was seen with a firearm or replica.