A St John ambulance officer has now died in hospital following a crash near Cambridge this morning.
The collision near Hickey Rd was reported around 3.45am and had already killed the driver of the other vehicle involved.
A stretch of the Waikato road – labelled a "death trap" by the regional Chamber of Commerce - was closed for at least 11 hours as the site was cleared.
Waka Kotahi said safety improvements were underway for the stretch of road between Cambridge and Piarere, which covers the site of the crash.
In a statement, Hato Hone St John deputy chief executive ambulance operations Dan Ohs said the ambulance officer, who worked as a patient transfer officer, had a "brave fight" after being critically injured and flown to Waikato Hospital.
However, the officer died this afternoon with their family by their side.
Ohs said the St John team were "devastated" and "grieving the loss of one of our own".
Chief executive of the Waikato Chamber of Commerce Don Good called the stretch of road between Hickey Rd, where the crash happened, and Piarere a "death trap" that had claimed "an unacceptable number of lives".
"Road users, local residents and Chambers have appealed for urgent action for the right safety measures to be put in place and have been ignored."
Waka Kotahi speed and infrastructure programme director Dave Van Standen said safety improvements were well underway for the road between Cambridge and Piarere.
"Our thoughts are with everyone affected by the tragedy. Any death or serious injury on a New Zealand road is unacceptable."
Several kilometres of median barriers had already been installed, including 2.4km from south of Ferguson Gully which had been hit 40 times since it was installed in 2020.
"That's 40 incidents which could have otherwise resulted in serious head-on crashes."
Just over 4km of median barrier was expected to be installed in the area in the 2022/23 construction season which runs until April.
Safety improvement designs for the 7.5km of road from the end of the Waikato Expressway to Fergusson Gully Rd were expected to be approved shortly however construction was not expected to begin before the 2023/24 summer.
Dan Ohs, from St John, said the ambulance officer who died was from Rotorua and was driving the ambulance from Hamilton to Rotorua with a registered nurse who is now in stable condition in Waikato Hospital.
There were no other people in the ambulance.
Ohs said the St John team were "devastated" and "grieving the loss of one of our own".
"What we can confirm is that the ambulance officer was a well-respected and long-serving member of the Hato Hone St John whānau.
"They are one of a very small number of ambulance officers to lose their life in the line of duty in New Zealand in the last 80 years."
Ohs said while the officer's primary role was within the patient transfer service, they were also active in their support of both Event Health Services and Emergency Ambulance.
In recognition of their service, they were admitted to the Order of St John as a Member in 2004, Ohs said.
St John would not be releasing any names at this stage as the family had requested privacy.
"Our focus remains on supporting our people and the police with their ongoing investigations into the crash."