MYSTERY surrounds the source of a large bang that rocked Cooranbong on Sunday about 9pm.
Residents reported houses shook, and animals were spooked.
It's believed the noise was heard most clearly around Babers Road and Cedar Cutters Crescent.
"But people as far away as Mount Nellinda Road said they felt it," a resident told the Lakes Mail.
A post on Facebook attracted 100 comments from concerned residents speculating about the cause.
Centennial Coal said the sound was not mine related.
A spokesperson for Lake Macquarie Police District said two police cars responded to reports of the noise.
The cars patrolled the area, but nothing of interest was sighted or reported, the spokesperson said.