A woman was reportedly stranded in flood waters in Riwaka as flooding left people stuck on the roof of their house.
As the Herald attempted to reach Riwaka, a police officer stopped the car and said the area was cut off because of significant flooding.
The officer said some people were stranded on the roof of their house because the river had burst its banks, and a woman had been swept away while driving her car.
He was unable to say whether the woman had been rescued.
However the police central command centre was unable to confirm reports from the ground of a woman being swept away earlier this evening and indicated this may have been a miscommunication.
"A woman got stuck in the water on the road when she tried to drive through flood waters. She was not swept away as far as we are aware."
Fire crews were called to the Uruwhenua in Tasman District around the same time to reports of a car under water on the Takaka Valley Highway.
The stretch of road runs alongside the nearly-bursting Takaka River.
It's unclear what condition the woman was in following her ordeal.
Cyclone Gita is making itself known around the Nelson area after a day of steady rain, with rainfall becoming heavier and strong wind gusts this evening.
The region is already soaked, with this the third severe weather event in two weeks.
Nelson City Council spokesman Paul Shattock said it now seemed likely the Takaka River would breach its banks before 8pm.
"There is the potential for significant flooding from the Takaka River. We've had significant rainfall over the Takaka catchment area, and so there is a very likely potential the river will breach its banks in the next hour or so."
Shattock said some people in nearby Motueka were self-evacuating because of localised flooding.
Those people are staying in the Motueka Recreation Centre.
"We have police on the ground who are managing evacuations, and the New Zealand Defence Force are assisting as well."
In Nelson, a civil defence centre has been set up in the Salvation Army hall on Rutherford St.
Many people have been unable to find accommodation after flights were grounded and campsites evacuated.