KiwiRail group chief operating officer Todd Moyle said an electrical fire in a signal cabinet has damaged signalling to the south of Newmarket on the Auckland metro network this morning.
"The fire has been extinguished and KiwiRail staff are on site and will restore the system as quickly as possible," he said.
"We are working with Transdev to re-route Southern Line trains along the Eastern Line from Otahuhu. At this point, the heaviest impact is limited to trains running between Penrose and Newmarket. Western Line trains continue to operate.
"We apologise for the inconvenience to Auckland commuters but safety must be paramount.
"The cause will be investigated."
Mayor Phil Goff tweeted that he had been briefed by KiwiRail about a fire at the Newmarket signal box causing train disruptions on the Southern line.
"KiwiRail is looking at options to redirect trains but the Southern line will experience significant disruptions this morning," Goff said.
Commuters have reported confusion at train stations with poor communication from staff about the situation.
"Trains only going to Grafton and our train just sitting at Swanson," said one commuter.
"No communications at all in app and train staff aren't 100 per cent sure [what's] going on.
"[People] racing to get buses or take cars."
