The boy and his mother were flown by Northland Emergency Services Trust helicopter to Whangarei Hospital where the child spent the night in a stable condition.
Ms Young had been sitting at her computer at home across the road from the beach when she became aware of raised, alarmed voices and realised something was wrong.
She rushed out and saw people running down to the water.
"I just bolted across the beach to where two other men were already running into the water," Ms Young said.
A strong swimmer, she reached the man first and got him in a rescue hold.
She and one of the other helpers dragged him ashore while others brought in the distressed child.
Ms Young said the channels at Ngunguru ran quite fast in the out-going tide but locals were usually aware of the conditions and she had never considered it a dangerous beach.
"It just blew me away that it could happen in this quiet little place," she said.
Whangarei teenager Brad Olsen was visiting his grandparents further along the beach when the drama began to unfold.
Mr Olsen said he did not see the incident in the water but described the surreal atmosphere as medics tried for a long time to revive the man.
It was low tide and the desperate lifesaving attempt was taking place where the man had been dragged only metres from the water.
During that time the main road through the Ngunguru settlement was closed so the NEST helicopter could land there, Mr Olsen said.
Onlookers saw the boy and his mother loaded into the helicopter.
Mr Olsen said an air of shock hung over the scene.
He said it all seemed so strange.
"We've had this great summer and there were still people out there enjoying a summer evening, and this tragedy happens," Mr Olsen said.
"There was very definitely a sense of shock over the place," he said.