One of the Grimmer’s family members said he was devastated to learn his aunt and uncle had died.
The principal of Te Awamutu College, Tony Membery, has opened O-Tāwhao Marae for a tangi.
He said a representative of the victims’ families had approached the school about the use of the marae.
Membery said: “We express our condolences to extended whānau and friends of those who have passed. We will continue to be of assistance in any way we can”.
The crash happened at 4.44pm on Tuesday on State Highway 3 near Te Awamutu.
Inspector Jeff Penno said the two cars collided after one crossed the centre line.
Earlier, he said the cause of the crash could go unknown for months.
“We do not understand why it happened,” Penno had said.
Police would check whether either driver was impaired.
“While we always look at the environment, early indications are that roading factors on this particular piece of road are not at fault.
“Impairment is always something we look at, to ensure all drivers are sober, not just alcohol but illegal and legal drugs and that is certainly a focus of this accident.”
The Serious Crash Unit had conducted a “meticulous scene examination” on Tuesday night.
“And the findings from that examination and forensic evidence obtained will feed into a crash investigation, which is likely to take several months,” Penno said.
‘It was mangled’ - witness
Meanwhile, a man, who did not wish to be named, earlier told how he drove past the crash while medics were arriving.