Fire and rescue personnel say they’re “not giving up hope” in the search for a missing mother and baby after an explosion in the shop below their home in the Sydney suburb of Rozelle.

Fire and Rescue NSW Superintendent Tom Cooper said rescue teams were using state-of-the-art devices in a race against the clock to find Bianka O’Brien, 31 and her 12-month-old son, Jude.

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“At this stage, the first 24 hours of any operation like this is critical,” said Supt Cooper.

“As time diminishes, so does the chance of finding survivors.”

“We won’t be taking any shortcuts, it’s a long operation, but we won’t leave the site until we make sure everbody is accounted for,” he said.

Emergency personnel are yet to establish the cause of the large explosion at a convenience store in Rozelle in the early hours of Thursday morning.

Supt Cooper said there was a lot of rubble at the site.

“When I arrived at the site yesterday afternoon, it was very reminiscent of Christchurch,” he said, referring to the massive Christchurch earthquake in 2011.

“We’ve got about 55 figreighters on scene at moment and we will matintain that until we get through this rubble,” he said.

NSW Police Acting Superintendent Clive Ainley confirmed that an adult male was recovered from the building at 11pm last night, but was yet to be identified.

Supt Ainley said that police investigations would not start until the rescue operation was over.

“At this stage we haven’t got a hold of the crime scene to determine the cause of fire and where it originated,” he said.

“The investigation takes second place against the rescue… When fire and rescue have done their job, we will start our forensic investigation at the scene.”

Supt Cooper said that the search and rescue operation would take time as the structure was still unstable.

“It’s a very slow operation at this stage. We have to account for the safety of the fire fighters and police personnel at the site,” Supt Cooper said.

“So far we haven’t found anything or anyone but we haven’t given up.”