RNZ reports fifty-three people were on the bus when it plunged down a steep bank killing Sione Taumololo, 11, and Talita Fifita, 33.
The pair were part of a group of school students and band members who were in New Zealand on a four-week fundraising tour.
Family, friends and members of the wider Tongan community were among those who were at the memorial service at the Tongan Methodist Church in Grey Lynn.
Many of those who were on the bus when it crashed were also there, and a number of them had visible injuries.