Thinking a car had crashed he ran on to the street and saw the ground level of the house across the road explode in flames, and smelt gas.
"The front of the garage door just went boom in a huge explosion," he said.
"The flames lit the place up like a candle. Then there was screaming from inside."
Other neighbours joined him seconds later.
"I saw the garage door literally fly across the road," said neighbour Wendy Kennedy. "I was yelling out her name."
As flames engulfed the house, two other men joined Dacre and followed the sound of the screams. One man ran into the house and up the stairs towards Bills, Dacre said, with no regard for his own safety.
The three men dragged Bills, a teacher believed to be aged in her 50s, down the stairs.
The heat and debris added to the difficulty as they carried her out: "The soles of her shoes were melting and burning through my hands," said Dacre, whose hand sustained injuries in the fire.
The group carried Bills, who was still conscious, on to the street and doused her with water using a nearby hose until emergency services arrived.
She suffered extensive burns to most of her body, including her face, hands and legs.
Thirty seconds after getting her out, there was another explosion from the house. "We were bloody, bloody lucky," said Dacre.
Dacre did not consider himself a hero - he said he simply did what anyone else would have. "Us guys who were there at the time, we just sort of reacted. It was just purely about getting her out of there."
But neighbour Kennedy paid tribute to the men's courage: "Twenty seconds later she would have been dead."
The force of the explosion pushed the car 10m out of the garage and on to the street. The men smashed a window to free the woman's two dogs, Bella and Ratty, who were trapped inside.
The dogs were not injured and Kennedy was looking after them yesterday, after their owner was admitted to hospital.
Kennedy said Bills lived alone and had been in the street for least 10 years, working as a teacher from home.
Bills was taken to Middlemore Hospital, where a spokeswoman said she was in a stable condition.
