A loud rumble shocked and confused Dunedin residents on Thursday evening, sending social media into meltdown.
Hundreds of people took to social media pages in an effort to figure out the source of the mysterious sound.
There are suggestions it could have been thunder or even a meteorite.
A Dunedin resident told the Herald it sounded like a cannon firing on Anzac Day and also thought it was an earthquake but there was no shake.
"Was up the main street of Mosgiel when I heard it," one woman wrote on Facebook.
"Thought it was just a plane taking off and with the direction of the wind sounded louder than normal!"
"I thought that noise was the drunk guy upstairs falling over again," another said.
"Yeah we get it everyone heard it, nobody has any idea what it was tho by the looks," one added.
"I must be the only one who didn't hear it. I've not even got anything loud going on. Weird," another said.
The noise was reportedly heard near the Dunedin Airport in Outram, towards Middlemarch and as far away as Queenstown and Palmerston too.
Metservice reported the weather for Dunedin at the time was cloudy with light showers and with southwesterly winds, strong about the coast but without mention of thunderstorms.
No earthquakes were registered on Geonet for the Dunedin region.