Emergency services struggled to get to the injured after a six-vehicle pile-up on a wire-barriered section of the Hawke's Bay Expressway in peak-hour traffic.
Six people were injured – one seriously and five moderately – during the crash in foggy conditions near Greenmeadows about 8.17am Monday.
A dashcam video from another driver on State Highway 2 at the time showed a concrete truck crashing into the back of a car with significant force, shunting it into a ute in front.
The traffic in the area at the time meant other cars, many of them work vehicles, were also caught from behind as vehicles hit each other like a "concertina".
Hawke's Bay road policing constable Steven Knox said the visibility in the area at the time, particularly travelling towards Hastings, caused a backup in traffic that a concrete truck driver didn't see in time.
"The truck driver reacted too late and didn't realise the vehicles up ahead had stopped," he said.
"The car took the full impact of the concrete truck and pushed the rear compartment right up to the driver's seat. It also shunted it into the vehicles in front, which caused a concertina-effect ahead of them."
Knox said the chassis of the car was severely damaged, while the woman driving was trapped and had to be cut out.
Drivers crawled through the fog and subsequent backed up traffic during peak hours, which meant all three emergency services – police, ambulance and fire – had trouble getting to the scene, Knox said.
"The amount of traffic on the road and the barriers meant we had limited places where we could merge in and make our way through," he said.
"Fire crews especially had difficulties getting to the crash scene."
A St John Ambulance spokeswoman said the first set of three patients transported via ambulance arrived at Hawke's Bay Hospital about 9.30am.
Due to the busy roads, the second set of patients arrived at hospital about 9.58am.
A Hawke's Bay District Health Board spokeswoman said four of the injured people have been discharged from hospital, while two still remain in hospital.
Four men – two in their 40s, one in their 50s and one in his 60s – were assessed and discharged.
A woman in her 30s was
this afternoon in a stable condition in a ward, while a man in his 40s was still being assessed.
Waka Kotahi Regional Transport Systems Manager Oliver Postings said crashes involving this number of vehicles during peak traffic hours can be challenging for emergency services to respond to.
"It is up to them to determine how best to navigate these challenges and they do an excellent job of doing so, safely and quickly," he said.
"We would also expect motorists to be considerate and do their best to move aside to allow emergency vehicles to get past."
Postings said a debriefing with emergency services to better understand what the issues were in this incident will also take place.
The Hawke's Bay Expressway was closed between Taradale Rd and Meeanee Rd, but reopened by 11am.
Three fire trucks and three ambulances attended the scene, while the Serious Crash Unit had begun an investigation into the crash.
Napier Citizens Environmental Advocacy Centre Secretary Ken Crispin has called for the introduction of speed cameras or flashing warning lights in the notoriously foggy area to warn road users to slow down.
"Speed has to be reduced on the approach to Napier," he said. "We've talked to NZTA many times and want battery controlled flashing screens on the roadside."
"The people of Napier have had enough."
The crash was not the only one to cause trouble in the region over the past 24 hours.
On Sunday another person was seriously injured following a single-car crash on Korokipo Rd in Fernhill, Hastings.
Emergency services were called to the crash about 10.46pm.
A St John Ambulance spokeswoman said one person with serious injuries was taken by ambulance to Hawke's Bay Hospital.
Earlier Sunday evening, a person also sustained minor injuries after a crash on Taihape Rd, Waiwhare, Hastings.
Three fire trucks attended the crash about 7.33pm.
A Fire and Emergency New Zealand spokesman said a car was found on its roof between Army Rd and Waiwhare Rd.
The road was cleared shortly before 9pm.