"They had lunch under a tree before they went to look around the park with the kids."
He said Toromon and his 11-year-old brother Totira suddenly "took off".
"They were just playing, running around, and they left the group. That's when the accident happened. They were out of sight of the mum and dad.
"Toromon jumped onto the fence and just started walking and slipped, then he fell into the mud."
He said Totira was momentarily caught between the impulse to pull Toromon out or run for help.
But hearing his cries he reached over the fence and grabbed him. "He took him on his back to the grass and then a lot of people came."
Toromon was taken to intensive care at Middlemore by air ambulance and at first it wasn't thought his injuries were life-threatening.
But the next day Toromon's father phoned Tauman to say they needed help - their son had only a 5 per cent chance of survival. By Thursday, he was dead. Tauman said the boy's parents had asked if higher fences might stop a similar tragedy: "Even with danger signs, you can't always control kids running around."
The family - who have eight surviving children - would stay in the city they moved to two years ago, he said. "Now that they have buried Toromon here they will never leave this place. It's part of their family, Hamilton."