Emergency services were called to the scene just before 3pm on Saturday, where two motorcycle riders had crashed during an international racing event.
The event was called "Sound of Thunder" and run by Bears Motorcycle Club and it said it was going to feature "iconic bikes from past & present, including the legendary Britten Motorcycle & a Moto2 replica bike".
Hato Hone St John earlier said it transported the two riders to Christchurch Hospital, one in a critical condition and one in a serious condition.
On Wednesday, police confirmed one of the riders had died following the crash.
Police didn’t provide an update on the other rider.
It follows a terrible weekend for the motorsport community, after a double fatal crash during a rally in Northland on Sunday which took the life of a promising young driver and a beloved husband.
The driver and co-driver died in the single-car crash at about 2pm during the Arcadia Road Rallysprint in Paparoa, held by Hibiscus Coast Motorsport Club.
The fatalities occurred when the car left the road and became submerged in a swollen river, according to a police serious crash investigator. Because the crash occurred while the road was closed, the events will be investigated by WorkSafe and MotorSport New Zealand.
Tributes reveal the driver was 15-year-old Brooklyn Horan, who was showing promise behind the wheel despite his young age, and co-driver Tyson Zane Jemmett.
A social media post by Hodgson Motorsport shared a photo of Horan competing and winning in Kiwitrucks competitions as far back as 2017 when he would have been under 10.
"It is with a very heavy heart that today we heard the absolutely devastating news that Brooklyn passed away doing the very thing we grew to love together as families," the tribute reads.
Meanwhile, Jemmett, 35, was remembered as a keen motorsport enthusiast and beloved husband.
He worked at media organisation Stuff, alongside his wife Lucy, the website said on Monday afternoon.
Jemmett’s family released a statement confirming the death of a "beloved husband", and loved son of Ian and Pat, brother of Kahlia and loved son-in-law of Caroline and Glenn, Stuff reported.
Police serious crash unit investigator Jeff Cramp surveyed the scene of the crash on Sunday, with his report being sent to WorkSafe and MotorSport New Zealand.
The crash occurred when the car came off an unsealed road and into a river swollen by rain, with safety equipment in the car possibly making it harder for the pair to get out, he said.
"Rally cars have whoopsies all the time when competing, just the difference in this one is the fact the car went into a swollen stream and was submerged," Cramp said.
"Tragically, they couldn’t get out of the vehicle. That’s the fundamental difference: the fact that it went into a swollen river and submerged."
WorkSafe said it has been notified and is making initial inquiries, before deciding if it will begin a formal investigation.
MotorSport New Zealand president Wayne Christie said the organisation will undertake a full and thorough investigation into the incident, working with event organisers and volunteer officials, as well as co-operating with police and WorkSafe.
