The Hawke's Bay Rescue Helicopter transported two people to hospital while the other two went by St John ambulances, two of which had arrived from Taupō and one from Napier, all of which arrived on scene about 5pm.
The road was closed for four hours, with vehicles at both ends turned back, and did not fully reopen until just after 3.30am.
Eight deaths have already been recorded from five separate crashes on the road from December 2019 to June 2020.
A week ago 10-year-old Teang Atauea died in Hawke's Bay Hospital after a crash in a nearby stretch of the road on June 23.
Napier station senior fire officer Glenn Drew said the car had effectively rolled onto its back during the crash, and the woman was trapped inside.
Using cutting equipment, they were able to clear a path to put her onto a stretcher and then get her to the rescue helicopter.
"For some reason it's almost always in and around Te Haroto.
"I don't know what it is about that stretch, but 60 to 70 per cent of the time, when we're called it's for that area."
Te Pohue nearby has a volunteer fire brigade trained to deal with medical events and securing scenes but do not have access to the specialist cutting equipment that paid fire brigades in Hastings and Napier do.
Hawke's Bay principal rural officer Trevor Mitchell said it was a similar situation in Putorino on State Highway 2 between Bay View and Wairoa.
"The reality is that some parts of Hawke's Bay and New Zealand are pretty remote. That's an isolated stretch of road."
Truck driver Antony Alexander, who has called for safety improvements on the road, said he didn't believe there was much more emergency services could do in these situations.
However, there was a desperate need for cellphone coverage in the area to prevent the potential for even more delays, he said.
