A house-shaking explosion noise has baffled Auckland residents.
The mammoth bang was heard by residents in the suburbs of Onehunga and Mangere Bridge about 10.30pm on Sunday.
One reader who wrote in to the Herald said they could feel the house shake.
The scary noise sounded "super sonic" and no one knew what it was, the woman said.
Residents turned to Twitter to find the source of the mysterious noise - but no clues have turned up yet.
Dean Taylor tweeted: "What was that Big Bang in Onehunga just now?"
Twitter user Peter Tainui said it might have been related to the mystery bang or explosion heard in the same area a couple of weeks ago.
"What/who the hell is the cause?" he asked.
Another loud bang stumped residents in the Onehunga, Three Kings, Mt Roskill, Epsom and Mt Albert area on May 30.
One Twitter user at the time said it sounded like a loud boom, thunder or an explosion.
A series of mysterious explosion noises were also reported across Auckland in June 2014, which turned out to be Defence Force training exercise at the Kaipara Bomb Range.
New Zealand Defence Force spokesman Geoff Davies said the noise did not come from the organisation.
He said the Defence Force had not received any calls about the noise.
An Auckland Council spokeswoman said there was no known record of calls about the bang on Sunday night.
Another loud bang was reported by central Auckland residents in May when a power line worker was injured in a substation accident, cutting power to homes.
But there was no power outages or incidents on Sunday night, Vector spokeswoman Sandy Hodge said.
The company had "a really quiet weekend", she said.