"The smoke was really bad and the woman eventually had to jump from the window herself."
Emergency services were called to the house and found it "well ablaze".
Withy and another male had rushed to help and dragged an unconscious man from a downstairs room to safety.
Next-door neighbour, Fakaola Uilou, tried to beat back flames with a garden hose.
"A man, who I believe is the father, was overcome by smoke," Withy explained. "He had black saliva coming from his mouth and we thought he was gone.
"When we got him outside he eventually came round and was trying to get back into the house and get upstairs as there was another wee boy still in there. We had to hold him back."
Fakaola Uilou, 18.
Another neighbour, Maria Moeroa, said she took the two boys who escaped to her house.
"There was pure panic going on and the wee boys are only about 5 and 6 years old. The family involved have about four kids and they are a really nice, quiet bunch. It is so sad another child was trapped in the house. It all happened so quickly, it was frightening."
Fire services at the scene on Malone Road. Photo / Daniel Hines
Firefighters pulled the remaining boy from the property and he was revived at the scene, fire service area commander Mike Shaw said.
"The toddler, aged about 2, was unresponsive at first but they managed to get him going again," he said. "The child was taken to Middlemore Hospital and an adult was taken to hospital too."
Shaw could not say if active smoke alarms were in the house.
The blaze happened on the same day two Hamilton families farewelled loved ones killed in last weekend's fatal fire.
Connor James Swetman, 17, Toni Maree Johnston, 23, and Jake Hayes, 19, perished in the Collingwood St house fire early last Saturday morning. Hayes was farewelled on Friday.
Bagpipes skirled at Hamilton Gardens yesterday where hundreds said a last goodbye to Johnston.
Mourners gather at the funeral of Toni Maree Johnston, who died in a house fire last weekend in Hamilton. Photo / Doug Sherring
Her brother, Greg, said words could not describe how tough this week had been for the family, but the flood of support had been "incredible".
Earlier, hundreds of mourners, many of them teenagers, attended Swetman's funeral.
Speaking on behalf of the family, celebrant K-M Adams described an outgoing young man who was "annoyingly good at everything he did".