Mr Cross said the name of the deceased might be released later in the day, but had yet to be confirmed.
"At this stage all we know is that unfortunately a family has lost a son."
The crash took place when it was still dark and police serious crash investigators were early this afternoon completing a survey of the crash scene to get a picture of how the tragedy had unfolded.
Mr Cross said the road through the area would probably remain closed until at least mid-afternoon. Traffic was detoured through the Arahura Valley and Blue Spur.
"We are anticipating it to be open to at least one lane by about 2 o'clock."
Contrary to other media reports that the vehicle involved belonging to a trucking company, the light truck was a private vehicle, Mr Cross said.
A national police media centre spokeswoman advised that the crash investigation was partly reliant on Tasman police district serious crash investigation staff arriving from either Nelson or Blenheim.
"The road is definitely still closed and will be for the next few hours," she said.