A helicopter has also been called to the scene.
One person has died in a two-vehicle crash on the Waitotara river bridge.
Police were informed of the accident on State Highway 3 at about 8.25am today.
A St John spokesperson said a helicopter is being sent to the scene on State Highway 3.
Police say the road is expected
to remain closed for some time, with motorists at the scene advised the closure is likely to be in place for two to three hours. Around 25 trucks are stuck in traffic or parked on the side of the state highway.
The NZ Transport Agency (NZTA) says there are no short detour routes available so motorists are advised to delay their travel while the road is closed.
