Sydney siege: Sunrise host Natalie Barr breaks down live on air after discovering hostage victim Katrina Dawson was sister of her friend

Ms Dawson died trying to protect her pregnant colleague

Natalie Barr broke down live on air

An Australian presenter broke down live on air as she discovered one of the Sydney siege victims was the sister of her friend.

Channel Seven’s Natalie Barr became visibly upset as she named Katrina Dawson as one of two hostages killed during a 16-hour siege at a Lindt café in Sydney’s Martin Place, close to the television network’s studios.

Katrina Dawson, a 38-year-old barrister and mother-of-three who worked in Sydney's central business district was named as a victim alongside Tori Johnson, a 34-year-old café manager, shortly after police officers stormed the café in the heart of Sydney’s business district.

"I'm just finding out that Katrina Dawson was the sister of a prominent barrister, Sandy Dawson, who has done some work for Channel Seven," Ms Barr said, her voice breaking.

"Who I know and who I have friends who know. She was a mother of three children”. Between tears, the Sunrise host added: “We’re just finding that out now.

As she sobbed, her co-host David Koch continued: “A mother-of-three, […] is one of the fatalities. This is a city with a heavy heart this morning.”

Gunman Man Haron Monis, known for sending “offensive and deplorable” letters to the families of Australian troops killed in Afghanistan, died after police stormed the café and seized the hostages in the early hours of Tuesday morning.

Monis, who came to Australia as a refugee from Iran, complained of being tortured in prison for his political beliefs and said he was fighting for Islam and for peace.

New South Wales detectives are investigating whether the two hostages were killed by the gunman or died in the crossfire.

Speaking to reporters, Australian Prime Minister Tony Abbott paid tribute to the hostages as "decent, good people" caught up “in the sick fantasy of a deeply disturbed individual".