Emergency services expected to remain at the scene of a fatal crash south of Christchurch until about midnight Tuesday.
One person was killed when a truck and two cars crashed on the Rakaia Bridge, on State Highway 1 between Christchurch and Ashburton on Tuesday afternoon.
Two other people were injured.
One lane of the bridge has been opened, but is not likely to be fully opened until about midday on Wednesday.
In Auckland, police have reopened the Southern Motorway, which was closed at the Otara-Papatoetoe Interchange after a serious crash involving a truck and two cars on Tuesday evening.
In Northland, a three year old boy is dead after a crash involving a tour bus and two cars in Kaeo on Tuesday.
The police closed State Highway 10 and put diversions at Matauri Bay Rd to the south and Wainui Rd to the north for much of the evening.