The scene was a mess and it was difficult to tell how many people were in the car, he said.
"It was loaded with holiday gear, they were obviously heading somewhere or returning with a car packed to the gunnels.
"It was a horrific situation."
It was the same spot where 17-year-old Kelly Thompson was killed on September 30.
"Tragic when you see that little cross there with a santa hat on it and it's exactly the same place," Mr Mitchell said.
Two other people were killed on New Zealand's roads last night near Blenheim. The car they were travelling at speed in crashed into a power pole and caught fire.
A forensic confirmation of identification would be completed today.
The deaths brought the holiday road toll to 15 - already three more than last year's total for the entire holiday period.
The official holiday period, which began at 4pm on December 23, does not end until 6am on January 4.