Occupants of van that crashed into Queenstown river unaccounted for

Police are working to find out who was in a vehicle seen ploughing into a river in Queenstown last night.

Authorities are returning to the scene, on State Highway 6 near Victoria Flats Bridge, where a witness described seeing a van crashing into an 85km/h speed sign before going through a paddock and over a cliff into the Kawarau River.

"Motorists found crash debris on the side of SH6, Victoria Flats Bridge, about 6.40pm last night," a police spokeswoman said.

The vehicle seen crashing into a sign before ploughing into the Kawarau River in Queenstown last night. Photo / James Allan

"The crashed vehicle was found partially submerged in the Kawarau River [and] it was secured by wire rope last night to prevent it from moving."

A scene guard was also put in place overnight.

Police at the scene in Queenstown, where a vehicle ploughed off a cliff and into the Kawarau River. Photo / James Allan

The scene where a vehicle ploughed through a road sign, through a paddock and into the Kawarau River in Queenstown. Photo / James Allan

An investigation is now under way to figure out exactly who was in the vehicle at the time of the crash.

"At this stage, the occupants remain unaccounted for."

The vehicle, understood to be a van, had been travelling towards Cromwell when it crashed.