The blast shattered the wall of a second-floor unit on Clarence Street around 6:30 am.

NSW Fire and Rescue Superintendent Adam Dewberry said there had been “significant damage”.

“The wall, a double or triple brick wall, has literally blown out of the building off that second level,” Dewberry told Today.

“Furthermore, the explosion generated a substantial pressure wave, impacting nearby properties and buildings with the resulting shockwave.”

Falling rubble destroyed a car parked below.

Firefighters carried one male out of the wreckage, and that person has since been taken to hospital.

“Currently, our priority is to conduct a thorough search to ensure that everyone is accounted for, although we haven’t confirmed that yet, but we’re actively pursuing it,” Dewberry stated.

“But it is still a very precarious and dangerous situation for our firefighters to move in and around.”

Nearby resident Charlton said he was having “a nice cup of coffee” when the explosion happened.

”And then I heard these two loud bangs, and then I said, ‘my god, it’s like an earthquake going on somewhere’,” he said.

“So I went down and I saw this whole building come down … very scary.”