Witnesses said a van overtook three cars stopped at an intersection on Ketemarae Rd, near Normanby in south Taranaki. The van was on the wrong side of the road when it collided with the bikers, coming the other way round a sweeping curve.
One of the dead men was named by friends as Kelly Reardon, 39, a wood merchant from Waitara.
Last night Reardon's former partner Adrienne Ahu was on her way to Taranaki from Te Awamutu. She said they had an 11-year-old son and the news of his father's death was hard for him.
"We've just marked a sad occasion as just over a year ago Kelly's father died," she said. "Now we are dealing with this."
More than 100 bikers gathered near the crash and voted to continue their ride and complete the toy deliveries for needy children - in honour of their dead companions.
Bikers Rights Organisation NZ (Bronz) Taranaki chapter president Murray Heal, who arrived with the fire service after the smash, said the scene was a mess. "All the bikes were piled up on the side of the road. A friend was comforting Kelly after he had passed."
St John Ambulance spokesman Roger Blume said six men were taken to Taranaki Base Hospital, one critically injured. One of the men taken to hospital had been performing CPR on a crash victim, when he suffered a heart attack himself.
Last night, a hospital spokeswoman said a 24-year-old man with serious injuries was likely to be flown to Waikato Hospital.
Two men, aged 64 and 42, were in stable conditions in intensive care. Two more men, aged 22 and 27, were in satisfactory condition, while a 21-year-old man had been discharged.
Heal said Reardon was leading one group of bikers and did not have a chance to get out of the way. "The van crossed the centre line and came out of nowhere. Kelly didn't have time to blink let alone react.
"It was a very good day, good weather - it was just a stupid, tragic accident. It was a bunch of innocent guys going for a ride for a good cause. It was definitely no fault of the bikers."
The annual Round the Mountain toy run is organised by the Bronz group, and yesterday - the first day of summer - they travelled from New Plymouth via Bell Block, Inglewood and Stratford. After the crash, they continued round the mountain to end up at Oakura Hall.
Normanby Fibreglass Factory owner Paul Schrader said he raced out from the back of his road corner factory to a scene of carnage.
"It was horrendous, horrendous, mate."
He said up to 10 mangled motorcycles and injured riders were strewn across the road. One man was trapped beneath a gold "boy racer-type" van and died at the scene.
He said some machines had disintegrated on impact and one separated fuel tank sparked a small fire, which was put out before the fire service arrived.
"I took my forklift over to try to take the van off the guy but there was nothing much we could do," he said.
"There's been three recent fatalities within a 15km radius of here in recent weeks. It's not good."
Boyce Luke was one of the motorists who had stopped, when he was overtaken by the van.
The elderly Austin Rd resident was too shaken to talk with the Herald on Sunday but told his wife: "It was like dominoes. One went down, then another went flying over another one."
The police serious crash unit is investigating.