"I'd imagine he's pretty distraught though."
The train was not believed to have been moved from its tracks but it would need to be checked before it continued.
Mr Mackay said the crash was sufficiently away from the highway to avoid causing any traffic delays.
The age of the truck driver was unknown, he said.
The death came just as KiwiRail and the Chris Cairns Foundation, which promotes rail safety, had issued a warning to motorists and pedestrians to be careful at level crossings over the summer period.
More freight trains are routed through Wairarapa during the holiday period to allow for work on the main trunk line. APNZ