Lawyer Katrina Dawson was confirmed as the woman killed in the siege at the Lindt Chocolat Cafe in Martin Place. She died in hospital after being held hostage for more than 16 hours.

The 38-year-old was one of two hostages confirmed dead at the hospital after a gun battle between police and gunman Man Haron Monis.

Dawson was a barrister from Eighth Floor Selborne chambers in Phillip Street, and the younger sister of prominent defamation barrister Sandy Dawson and McKinsey & Company director Angus Dawson.

She was married to Paul Smith, a partner at law firm King & Wood Mallesons, according to the Sydney Morning Herald.

The mother of three was also a good friend of barrister Julie Taylor, who also worked at Eighth Floor Selborne Chambers. Taylor was also among the hostages at the Lindt Cafe. She was taken away from the scene on a stretcher.

Dawson was the daughter of prominent businessman Alexander "Sandy" Dawson, president of the Royal Sydney Golf Club and the former managing director and chief executive of food company Arnott's, and sculptor Jane Dawson.

The president of the NSW Bar Association, Jane Needham, SC, said it was "with a heavy heart and deep sorrow" that she informed members of the bar that Ms Dawson had passed away in the early hours of the morning.

"Katrina, together with two other members of the NSW Bar, were held as hostages during the incident at the Lindt Cafe in Phillip Street, Sydney, yesterday," Ms Needham said.

"Katrina was one of our best and brightest barristers who will be greatly missed by her colleagues and friends at the NSW Bar. She was a devoted mother of three children, and a valued member of her floor and of our bar community. Our thoughts are with her family at this time, including her brother, Sandy Dawson of Banco Chambers.

"Out of respect to Katrina's family, the NSW Bar Association will be making no further comment at this time."

The other victim was Tori Johnson, the cafe owner. The 34-year-old was shot dead after he tried to wrestle the gun from the hostage-taker inside the Lindt cafe.