No one had been found injured, police said, and officers were following "positive lines on inquiry" at this stage.
A resident on the street told the Herald she distinctly heard a "loud bang" some time between 2pm and 2.30pm.
'It didn't sound like fireworks' - neighbour
"I was watching Netflix in my room and heard this bang and echoing after it - that's why I knew it was a gunshot.
"It didn't sound like fireworks."
The neighbour, who only wanted to be named Sarah, said she did not think anything more about it until she saw a Herald notification pop up on her cell phone.
"It said there was an incident in Manurewa. I opened the story and saw it was Christmas Road and knew it was what I'd heard."
Because their street is a long one, she decided to walk to see whether police were near her house.
"There were about a dozen cops in front of a house closer to Mahia Road and I could see some were armed.
"One cop was running to a police car and about five of them had rifles."
Sarah said police appeared to be focused on one particular house.
Police are appealing to anyone who may have information into the incident to contact authorities immediately.
Can you help? Call Police on 105 or CrimeStoppers anonymous on: 0800 555 111