A woman has died in a devastating unit fire that sent flames pouring from windows on Tuesday.

The blaze broke out inside a first-floor dwelling in Randwick, in Sydney’s east, about 3pm, NSW Police said.

Fire and Rescue NSW crews extinguished the flames but the unit on Alison Rd had suffered significant damage.

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Sadly, a woman believed to be aged in her late 70s never made it out.

Authorities said paramedics treated her at the scene but she could not be saved.

The woman is yet to be identified.

Another resident of the complex, a man aged in his 30s, was treated for smoke inhalation.

“A crime scene was established and an investigation into the circumstances surrounding the fire is underway,” NSW Police said.

“As emergency services work through the scene, road closures are in place and motorists are urged to avoid the area.”

Those closures include two eastbound lanes on Alison Rd, near Royal Randwick.

The advice for drivers in the area is to reduce your speed and prepare to merge.

A report will be prepared for the information of the coroner.