The ambulance officer killed in a head-on horror crash in Waikato yesterday had served with St John for 55 years.

The driver of a silver Audi car died at the scene. The critically injured ambulance officer died in Waikato Hospital.

Hato Hone St John deputy chief executive of ambulance operations, Dan Ohs, said the officer was part of the patient transport service and was heading back to Rotorua from Hamilton at the time of the 3.45am crash near Cambridge.

Ohs said St John is "devastated" by the loss of one of its own.

"It's our role to go out there in the community and reduce the impact of road trauma, so this is very significant for us," Ohs told AM.

The crash between a car and an ambulance on State Highway 1 near Cambridge killed the Audi driver and two St John staff were injured. Photo / Caitlan Johnston

The ambulance officer also worked within St John's event health services and emergency ambulance service.

Ohs said the officer was admitted to the Order of St John as a Member (MStJ) in 2004.

"The ambulance officer was a well-respected and long-serving member of the Hato Hone St John whānau," he said.

• One dead, two St John staff injured in car v ambulance crash
• Waikato crashes: Roads claim three lives after two serious collisions in a day

A nurse was also in the ambulance and was taken to Waikato Hospital.

Ohs said they were in a stable condition today.

He said St John was alerted to the crash by a 111 emergency call.

"Our focus right now is to support our people and our thoughts are with them, their wider family, and friends at this difficult time.

"We are also supporting Police with their ongoing investigations into the crash."

No patients were in the ambulance at the time.

About 10km of the road was closed for around 11 hours as emergency services worked to clear the site.

12 trucks travelling south are queued up at the Karapiro Rd cordon waiting for the road to be reopened. Photo / Caitlan Johnston

The crash left debris strewn across SH1. The fronts of both vehicles were completely smashed in by the impact of the crash.

Local identity dies in SH3 crash

Just 30km away from the fatal Cambridge crash, an Ōtorohanga identity was killed in a collision on State Highway 3.

The crash closed the road between Te Kawa Rd and Te Mawhai Rd for nearly five hours yesterday.

Otorohanga local identity Karam Haddad (left) was tragically killed in a crash on SH3 in Waikato. Photo / Supplied

Ōtorohanga locals were shocked to hear that Karam Haddad had died in the crash.

Karam was one half of the well-known Haddad Brothers.

He and his brother John have owned Haddad Menswear in Ōtorohanga since 1965.