Police are still investigating the cause of the crash.
But the Herald has been told Mr Afaese was travelling west when he was cut off by another vehicle as he drove through a roundabout at the intersection of Old North Rd and State Highway 16.
He swerved to avoid hitting the other car, crossed the centre line and collided with the Subaru, mounting the smaller car's bonnet before flipping and rolling.
As the Mitsubishi rolled, Mrs Afaese was thrown out onto the road. Mr Afaese and two boys were trapped inside the vehicle.
After the initial collision, the Afaeses' car also slammed into a Holden Commodore, which then struck a Ford Falcon.
The driver of the car said to have cut off Mr Afaese drove on, but later called police to report his involvement.
Last night, police said it was too early to say if any charges would be laid in relation to the crash.
Rick Flego was travelling home to Parakai with his 13-year-old daughter when he saw the crash happen.
"It was just in front of me. I saw all the brake lights come on and I saw this big pile of mess from one side of the road to the other," he told the Weekend Herald last night.
"They had to smash the front window to get [Mr Afaese] out of the vehicle.
"He was in shock, he was dazed. He ran to his wife and he shook her vigorously.
"He was yelling, 'Wake up wake up, get off the road'."
Meanwhile, the two boys - both believed to be the couple's sons - were trapped in the wreckage.One of them of them was seriously injured.
"He was screaming from the back of the van because his leg was caught," Mr Flego said. "His leg was going in one direction and his body in the other direction.
"A couple of people were trying to look after him until the fire brigade got there to cut him out. He had lacerations on his face."
Fire Service staff cut the roof off the Mitsubishi and one of the boys was freed immediately.
They had to cut further to release the other boy's leg.
Three people, including the injured boy and the driver of the Subaru, were taken to hospital with serious injuries.
Mr Flego said the driver of the Subaru was able to get out of the car but was injured.
"He was covered in blood ... I don't know how he survived. He didn't know who he was or where he was."
The people from the other cars, including a husband and wife and their two little daughters, appeared uninjured.
Mr Flego's daughter sat with the younger girls as the adults directed traffic and tended to the injured.
He described the crash as "quite vicious".
"It all happened so quickly. It was a hard impact ... It was a close call. It's a bit surreal," he said.
A police source said last night that it was highly likely Mrs Afaese would have survived had she been wearing her seatbelt.
According to her Facebook page, she attended Massey High School and then Massey University.
She worked as a case manager for Work and Income New Zealand and had been living in Helensville with her husband and their children for about 10 years.
In other fatal crashes, Opotiki men Gordon Douglas Nelson, 67, and Frederick Michael Ruff, 70, died when the tow truck they were in left a narrow gravel road and rolled down a 30m bank on Thursday afternoon.
Twizel driver Yulane Margaret Cadigan, 44, was killed on the Fairlie-Tekapo Road in South Canterbury the same day.
Police said it appeared she lost control of her vehicle, which left the road and hit a tree.
Early yesterday morning, an 80-year-old male pedestrian from Ashburton was struck by a vehicle on the Hinds-Rangitata Highway, about 5km south of Hinds in Mid-Canterbury.
He died as a result of his injuries.
An elderly man died on Thursday after crashing his car into a tree while driving in heavy rain near Pukekohe on Thursday.
The Easter road toll period began at 4pm on Thursday and finishes at 6am on Tuesday. Last night, the holiday toll was three. Last year, the official toll for the entire Easter holiday break was three, up from none in 2012.
