A bridge near Arthur's Pass has been washed away as torrential rain causes rivers and creeks to overflow on the South Island's West Coast.
Meanwhile, emergency services in Greymouth are searching the Haupiri River after reports that a person is missing. The search began just before 8pm.
An image shared to Facebook shows the bridge leading to Arthur's Pass collapsed in the wild weather, as State Highway 73 remains closed in the area.
The damage caused to the bridge over Goat Creek, near Otira, is "significant", an NZTA spokesperson told 1 NEWS. The bridge was previously replaced in 2010.
The spokesperson said it will take some time to fix and NZTA will likely make a call in the morning about when the state highway is likely to re-open.
There are a number of slips and flooding along the highway, he said.
The weather has also caused a group of Otago Boys' High School students to become trapped in a hut in Mt Aspiring National Park with torrential rains making a creek impassable.
Deputy rector Mark Hooper told the NZ Herald the students were due to return from their trip today but the wild weather caused the creek to rise in level, becoming too high to cross.
The group of around 25 year-nine pupils are hoping to be able to walk out from the Matukituki Valley hut tomorrow and meet a waiting bus.
Mr Hooper said the group has good food supplies and all of their parents are being kept informed of the situation.
Earlier today, students at South Westland Area School on the West Coast had to be escorted home by police after flooding forced the closure of the school at lunchtime.
West Coast response manager Senior Sergeant Brent Cook has told 1 NEWS police have been helping students get home safely.
"Our job while working with Civil Defence is to ensure the safety of students and those at the school," he said.
"We escorted some kids home in police vehicles and working with the school and mums and dads to make sure measures were taken to ensure everyone’s safety."
State Highway 6 between Hari Hari and Fox Glacier was closed due to surface flooding.