By Luke Costin in Sydney

A heroic vet and her neighbours are being praised for saving the life of a shark attack victim who dragged herself out of the water at a Sydney Harbour bay.

Public servant Lauren O’Neill, 29, was bitten on the right leg by a bull shark while swimming near a jetty in Elizabeth Bay around sunset on Monday.

Michael Porter had just arrived home from work when he heard faint yells for help through his open window.

“It was absolutely mortifying, horrifying, I’ve never experienced anything like it,” he told Nine’s Today program on Tuesday.

“Lauren, the victim, was pulling herself up the side of the harbour pool, trying to get into the safe enclosure.

“Her leg was sort of trailing behind her – the water all behind her was all red blood.

“The whole thing was totally surreal and I still haven’t processed it all, to be honest.”

He was quickly joined by several other neighbours, including a “hero” vet named Fiona who applied tourniquets to stem the bleeding.

Ms O’Neill’s significant wounds meant “blood was everywhere” and, while in little pain, she struggled to maintain consciousness before paramedics arrived and rushed her to nearby St Vincent’s Hospital for surgery.

She was in a stable condition on Tuesday morning.

“Fiona is a hero and I believe she saved her life,” Mr Porter said.

“I’m not sure what would have happened (without her) but it wouldn’t have been good.”

The vet was also lauded by Deputy Premier Prue Car as a “legend” and Health Minister Ryan Park for having “quite possibly saved (a) life”.

Mr Park also thanked first responders and hospital staff who had “literally performed a miracle and kept this person alive”.

An analysis of the bite pattern led government officials to positively identify the predator as a bull shark.

Shark bites in Sydney Harbour are extremely rare but the area is an important habitat for adult and sub-adult bull sharks.

“It’s likely bull sharks are coming from Queensland’s waters, into NSW and into Sydney in the summer and autumn months for foraging opportunities,” government shark scientific officer Amy Smoothey told the ABC.

Tagging and tracking of nearly 100 bull sharks since 2009 has shown they use all areas of the harbour from Parramatta and Lane Cove Rivers to Middle and North Harbour.

They prefer water temperatures above 20C, slightly deeper water during the day and shallower water at night and are more active at dawn and dusk.

People should take extra care in murky, dirty water, after high rainfall or floods, where lots of baitfish and diving birds are around and within one kilometre of a river, the NSW government says.