KiwiRail has confirmed that barrier arms, flashing lights and warning bells were operating at a level crossing south of Auckland where a train and car fatally collided.
A four-year-old child died following the incident on Tuesday.
Three other children aged two, six and 12, from the same family were injured and are being treated at Starship Children's Hospital in Auckland. Two are in serious condition.
All the children were in a car their father was driving when it collided with a freight train at Paerata. The father was not injured.
There are conflicting reports as to whether the car tried to go around the barrier or got stuck on the track on its way over.
Police say it could be several days before they establish what happened.
A spokesperson for KiwiRail, Kevin Ramshaw, says the effects of collisions are widely felt and the accident is a reminder for care at level crossings.
Mr Ramshaw says such accidents are a traumatic experience for train drivers, who are often helpless to intervene, and are difficult for other staff called to the scene.
KiwiRail says it feels deeply for the family involved in the collision.