Three KiwiRail workers have been injured after a shunt locomotive derailed in Auckland.
David Gordon, KiwiRail's acting CEO, said the incident occurred at around 1.25am on Wednesday.
One of the workers was treated at the scene, while the others were taken to hospital for observation.
St John Ambulance said the pair taken to hospital were in moderate conditions.
The shunt locomotive had derailed near St Johns, damaging a section of the track.
Gordon said the damage includes a turnout and a set of signalling points.
The incident has affected Eastern Line trains, with Auckland Transport advising commuters to take buses instead.
"KiwiRail staff are on site and will work to re-open the line as soon as possible," Gordon said.
"A full investigation will take place to understand how today's incident unfolded, however it is too early to speculate regarding cause at this stage."