No charges have been laid and inquiries are continuing.
Meanwhile, Auckland Transport acting media relations manager James Ireland said AT was investigating the "extremely disturbing" attack as a matter of urgency.
"This event is extremely disturbing and we know it was very upsetting for the young people involved.
"We are sourcing CCTV to review and send to the police. We will work with the police in any way we can."
The two 15-year-olds were travelling to Avondale from Britomart Transport Centre in Auckland's central city when they were attacked on Saturday, August 12, about 5.30pm.
The mother of one of the victims, Jen de Montalk, spoke to the Herald yesterday and voiced her concerns on the alcohol-fuelled assault.
She said her daughter and male friend were travelling home on the train when they were confronted by five drunk men wearing Four Square costumes and masks.
"The kids were on the train near them and one of the men started walking around and telling my daughter to put her hand in his pouch, because he was wearing an apron.
""He then got his dick out and exposed himself to her," she said.
"Then one of the other guys suddenly took a disliking to the boy she was with. He called him a faggot, rolled up his sleeves and started choking him."
The shocking attack garnered viral attention after video footage and de Montalk's account of the assault illustrated the lack of help the teenagers received from train security and bystanders.
A Herald Facebook post with a link to the video footage has received more than 5600 likes, 1097 shares and more than 1000 comments from appalled readers.
One commented: "It should be illegal to watch a crime happen and Auckland Transport should be held liable. They should be responsible for our safety while we are using their services."
Another added, "Sadly this isn't the first case I've heard of Auckland Transport security not doing anything to stop harassment."
"[I've] been in a similar situation myself and a good friend, who did stand up for someone else, was the one who then got attacked. Shame on the people filming!"
Auckland Transport announced in June this year it planned to ditch "guards" from its trains.
In an earlier Herald article the Rail and Maritime Union claimed Auckland Transport plans to scrap 160 on-board train manager positions as part of major restructure of train services.
Train managers oversee the operation of trains, and are known as conductors or guards in other parts of the world.
The managers will be replaced by 18 transport officers.
As a result a train driver in a locked cabin could soon be the only person staffing most of Auckland's commuter trains.
Ireland told the Herald today that the number of transport officers would increase to 140, including supervisors, but the final number may be higher.
He said train managers employed by Transdev Auckland cannot issue infringement notices and do not hold any enforcement powers.
"AT has created a new public transport role in response to legislation passed last week. The legislation means AT transport officers will be able to issue infringement notices to fare evaders as well as provide assistance to customers."
He said another key differences between a train manager and a transport officer is that transport officers can be rostered to where they are needed most, such as at night or after school.
Other components AT is considering as part of the Security and Fare Enforcement (Safe) Project are more Hop electronic gates at stations, which are intended to reduce vandalism and reduce fare evasion.
Ireland says the consultation process is under way on the Safe Project but no immediate operational or on-board staff changes are planned.
De Montalk said her daughter spoke to police on Tuesday and they visited her friend at school the following day.
