Residents are waiting to return home after an explosion ripped through a three-level apartment building, trapping a man under rubble.
More than 50 firefighters and 16 fire trucks rushed to Lidcombe, in western Sydney, about 6.30am on Friday after multiple calls from residents.
The blast severely damaged the second floor, with walls blown out and ceilings shattered.
Police are investigating the cause of the explosion.
The man trapped under rubble on the second floor was rescued by firefighters and taken to hospital.
About 40 residents from three adjoining unit blocks were also evacuated.
Specialist urban search and rescue technicians are using laser monitoring equipment to detect any movement within the building.
Engineers are also working alongside the technicians to ensure the site remains stable, but the "structural integrity" of the six-unit block has been deemed unsafe.
Fire and Rescue NSW spokesman Adam Dewberry told AAP welfare agencies were onsite to help displaced residents.
