Some trains have resumed operation after a "signal issue" affecting all services across the Auckland network left many stuck on trains as they commuted to work.
On Friday at roughly 7am, a fault was identified on signals operated by KiwiRail, leading to the services being halted.
"All services have been stopped until further notice due to a network wide signal issue. Scheduled buses will accept rail tickets and AT Hop cards," the Auckland Transport (AT) said on Friday morning.
At 11am, AT advised that limited services had resumed operation on a half hour timetable on the western, eastern, Onehunga and southern lines as far south as Manukau.
"Rail replacement buses" are also operating on several routes, including between Papakura and Pukekohe, Panmure and Britomart, and Ellerslie and Britomart.
Automatic refunds have also been given to customers who have a registered AT Hop card and whose travel was disrupted this morning.
Other customers will need to go to a customer service centre for a refund.
At 9am, AT tweeted that all customers had been safely evacuated from trains that had been on the network when the fault was discovered.
Passengers had earlier taken to Twitter to vent their frustration.
One woman said she had been on a train outside of Britomart for 50 minutes, while another said they had been in the Britomart tunnel for nearly an hour.
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A Twitter account with the handle "AucklandTrains" said it recommended passengers found a bus.
"Damn, I'm stuck in the worst place ever. We can't go into The Strand and we can't go into Britomart," it said.
Another user said there had been no train movement at the Newmarket train station for roughly 20 minutes.
KiwiRail is investigating the fault and no trains will operate until further notice.