The body of a woman has been found beneath a collapsed Sydney unit complex as the NSW government says it’s investigating reports of a gas leak.

Rescue teams have found the body of a woman after an explosion collapsed a western Sydney unit complex.

A woman was missing and feared buried alive after an explosion on Waikanda Crescent at Whalan levelled most of the two-storey townhouse just before 1pm on Saturday.

She is being named in multiple media reports as Jasmin Mhey, and was the only person unaccounted for.

Locals have told Sydney’s Daily Telegraph that Mhey’s mother, Mercy, kept vigil from across the street as rescuers desperately sifted through rubble and debris.

Authorities said the body of a woman, yet to be formally identified, was found about 3.20am on Monday.

A report will be prepared for the coroner.

Five other people were injured in the blast. All have since been discharged from hospital.

Emergency crews had been working around the clock, combing the ruins amid increasing concerns gas had been leaking from the complex.

Speculation had been mounting since neighbours reported a smell over past weeks.

“There was always a gas smell … like a leak,” Andrew, whose grandfather lives in the complex, told 9 News.

Another neighbour said she felt unsafe and worried her home might also be affected.

“I don’t want to sleep here at all,” she told ABC News.

“My whole house is run on gas, I can’t even have a hot shower because they have turned it off [and] I can’t use my stove.”

“We could smell gas for the last two weeks,” another woman said.

While the cause of the explosion remains unknown, NSW Deputy Premier Prue Car said she was “deeply concerned” and that the reports of a gas smell were being urgently investigated.

NSW Housing Minister Rose Jackson said the explosion was a “devastating event”.

“I am deeply concerned to hear of accounts from residents who reportedly raised the issue of the smell of gas within the last 12 months,” she said.

“I have instructed Homes NSW to urgently investigate this matter. The department are currently checking maintenance logs for any history of this.”

NSW Fire and Rescue Commissioner Jeremy Fewtrell also confirmed there had been a leak at the site after the explosion, which hampered rescue efforts.

Fur units in the complex collapsed and nearby homes were also damaged in Saturday’s explosion, which was heard kilometres away.

Dozens of search and rescue technicians, including firefighters who responded to last year’s earthquake disaster in Turkey, were involved in the two-day rescue mission.

Firefighters used acoustic monitoring devices to capture sounds under the ruins while search cameras were used to peer under rubble and concrete slabs to look for possible survivors.

-with AAP