Two of the victims of a fatal crash at Matamata yesterday were a husband and wife from Hamilton.

Tributes have been posted on social media for the pair, who died along with one other person in a crash on State Highway 29 just after 5.30pm.

This morning police had no further information about the incident and said the Serious Crash Unit was still investigating.

Last night motorists were diverted as specialist officers examined the scene.

Today a family member of the couple said she woke up "stunned" to the sound of crying and howling as people learned of the tragic news.

Another said: "Rest in love to our uncle and aunty who showed us so much love".

"May you both rest in the loving arms of our father," she wrote on Facebook.

A friend of the couple said the news was "so sad".

"[They] always open their home to us when we went down to Hamilton," she said.

"She was always so nice."

Another friend posted: "Will never forget you both always and forever. Thank you both for everything."

The deaths were among six in the Waikato region this week.

On Wednesday, two people were killed when a car and ambulance collided near Cambridge, including an ambulance officer who had served with St John for 55 years.

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.

Later that day, 30km away, an Ōtorohanga identity was killed in a collision on SH3.

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

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.