"The car has actually hit the side of the train and it's spun around, so the back of the cab is non-existent.
"The female passenger of the vehicle was ejected from the vehicle and died at the scene."
The ute's driver was taken to Wairarapa Hospital with serious head injuries. Mrs Watson said it was a miracle he survived.
"It's amazing that anybody survived, with the damage to the ute."
The police serious crash unit had examined the scene but it was too early to know why the vehicle did not stop.
The crossing had no lights or barrier arms and a KiwiRail spokeswoman said the train would have been going about 80km/h when the collision happened.
She said it was one of many uncontrolled level crossings around the country.
About half of the country's 1400 level crossings have some electronic warning systems such as flashing lights, bells or barrier arms but there are still about 26 crashes a year between cars and trains.
The spokeswoman said it was too early to say if the fatal collision would prompt a review into the safety of the Wiltons Rd crossing.
"KiwiRail urges people to be really cautious around rail lines and when they're crossing lines," she said.
Last year, former test cricketer Chris Cairns launched a national campaign aimed at preventing deaths at level crossings.
Rail Safety Week was aimed at both drivers and pedestrians, and its main message was: "Use your brain, tracks are for trains."
Cairns became a rail safety campaigner after his sister Louise died in 1993 when a truck drove into a train she was travelling on.
At the time, KiwiRail chief executive Jim Quinn said: "Every single death or injury on the railway network is avoidable if people approaching it actively recognise the hazards that exist and obey the warning signs and signals."
Dangerous crossings
* There are 1330 level crossings around the country.
* 278 are protected by barrier arms and lights.
* 423 are protected by lights and bells.
* 629 have Stop or Give Way signs.
* 51 per cent of crashes happen at crossings not protected by bells and/or barriers.