All train services in and out of Wellington have been suspended by a fault.
Metlink said there were bus replacements for all lines but they may not be running to the timetable.
Greater Wellington Regional Council spokesman Jim Flack said there was no estimate on how long the trains would be out.
He said thousands of people would be affected.
"Between the hours of 10 and 3 there's 1200 people an hour going through Wellington stations.
