Police have urged people in west Auckland's Muriwai to evacuate. This follows reports of a house collapsing due to a slip.
Meanwhile, some communities on the east coast of the Coromandel Peninsula are already cut off, and many more face the situation if the Karangahake Gorge closes later tonight, Waka Kotahi says.
The agency expects the situation in the region to deteriorate further overnight as Cyclone Gabrielle hits the country.
"The full force of Cyclone Gabrielle is making itself known in the Coromandel and East Waikato, causing extremely dangerous driving conditions due to slips, flooding, storm surges and debris on the roads.
"The gorge is being monitored and a traffic management team is in place to ensure a closure can be implemented quickly should flooding occur."
Waka Kotahi is urging everyone that can to stay home.
Elsewhere, thousands are without power in Auckland and Northland, Coromandel an the Bay of Plenty. Evacuations have been underway in Auckland, part of the eastern Bay of Plenty coastline, parts of Tairāwhiti and Whangārei.
States of emergency have been declared in Northland, Auckland, Thames-Coromandel, Waikato, Hauraki, Bay of Plenty, Whakatāne, Ōpōtiki and Tairāwhiti as Cyclone Gabrielle starts to wreak havoc.
* Read more: Cyclone Gabrielle's impact in numbers
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