The town of Te Karaka in the Gisborne region will be cut off until tomorrow morning, Civil Defence says.
The region has been hit by flooding due to heavy rain, forcing the closure of rural roads, schools and inundating the basements of houses near the Waimata River.
Gisborne Civil Defence controller Peter Higgs said Te Karaka was cut off on both sides with the closure of State Highway 2, which would remain closed between Gisborne and Opotoki overnight.
"The decision will be reviewed at 9am tomorrow. The road is flooded at two points and the river [Waipaoa] has not dropped as quickly as we were hoping and we have to keep that road closed overnight," he said.
He said the Gladstone Road bridge in Gisborne was also out of action.
"That will be closed overnight, we've got a digger working on it to try and remove the debris that's jammed underneath. There's a lot of debris held up against the piers.
"It's also a bridge that carries power, gas, sewage, water so it's quite a crucial lifelines bridge."
Mr Higgs said the power and gas had been cut off and been re-routed to homes.
He said the major problem now for Gisborne Civil Defence was ensuring rural school students that travelled to Gisborne to attend Gisborne Boys High School, Gisborne Girls High School and Lytton High School were looked after.
"For the school kids from Te Karaka and other highs schools that come to Gisborne and also some of the people who work in Gisborne. We've contacted the schools and most of the schools have other contingencies or whānau or family they can stay with."
He said people wanting to find out which rural roads were closed should go to the Gisborne District Council website.
For more information on road closures and river levels, check the Gisborne District Council website.
The flooding has left some drivers stranded on State Highway 2 north of Gisborne, but police said they were not in any danger.
Officers are making their way to vehicles trapped by floodwaters north and south of Te Karaka. They do not know how many vehicles are on the road.
Police are telling drivers to delay all travel on the highway overnight.
Gisborne has had 150 mms of rain in 24 hours and the hills behind 200 mms, swelling the Taruheru and Waimata rivers to levels some residents say they have not seen before.
A high tide late this morning had the city rivers running higher than they have been for some time.
Some city residents along the banks of the Waimata River that flows through part of the city had put sand bags in place at their properties.
Inundated with sewage
A pregnant woman and her two children have taken refuge in a holiday camp after raw sewage flooded their Gisborne property.
Civil defence officials say the basements of some houses next to the Waimata River have been inundated with water.
Korey Price said raw sewage flooded her back garden before mingling with the floodwaters at the front of her house.
She said she was not prepared to take the risk of staying put when she was pregnant.
Both Tolaga Bay and Te Karaka area schools were closed this morning.