A woman has escaped a fire by jumping from the second storey of a unit complex while her pet cat has received oxygen treatment.

The blaze had taken hold at the Neutral Bay complex in Sydney’s lower north shore about 5am on Friday.

The woman threw a mattress out the window after becoming trapped by flames and smoke in the hallway.

Neighbours who evacuated when alerted by smoke alarms placed the mattress on top of bins before the women leapt onto it.

A pet cat was also rescued from the scene by firefighters who placed it on oxygen before rushing it to a veterinary clinic.

Fire and Rescue NSW would not reveal the cat’s condition.

NSW Ambulance treated the woman for lower leg injuries and another woman who suffered burns to her legs.

Both were taken to Royal North Shore Hospital.

Authorities believe a spirit burner started the blaze that broke out in a ground-floor unit.

– AAP