Manurewa resident Gabrielle Hansen was woken up at 4.30am by someone screaming and banging on her front door.
But by the time the 52-year-old housewife reached the door, the person had left.
Minutes later, Hansen said, her neighbour's house was swarming with ambulance, police cars and a fire engine.
"It was like in the movies, and I couldn't believe it was happening on our street," Hansen said.
She went to speak to the police, who told her a man had died in the house.
Police were called to the address at 4.52am this morning, a police spokeswoman said, and found a man in a critical condition.
CPR was administered at the scene, but the man died from his injuries.
One person was assisting police with ongoing inquiries and no one else was being sought.
Hansen said she felt "stunned" because there was only one man living at the address, and he was her "mate".
"He would often come over and we'd chat about anything and everything over smokos," Hansen said.
"He's my mate and, if it's really him that's gone, I'm gonna be really missing him."
She said four people lived in the house - the man, his wife, stepdaughter and her baby. They have been neighbours for about four years.
The man's wife would also sometimes bring over cakes and yoghurt, Hansen said.
Hansen's daughter, Dalice Hansen, 32, said she saw the stepdaughter being taken away in a police car.
"They are an awesome family and awesome neighbours," Dalice said.
"I just can't believe this has happened."
Housing New Zealand has confirmed that the property is a state house.