12/16/2014 07:46 EST | Updated 02/15/2015 05:59 EST

Natalie Barr, Australian TV host, cries on air for slain Sydney hostage

An Australian television host broke down and cried during a live broadcast as she told viewers that one of the hostages killed in Sydney was the sister of her friend.

Natalie Barr was overcome with emotion on Channel 7's Sunrise news program Tuesday when she revealed the name of Katrina Dawson, a 38-year-old mother of three who was killed during the 16-hour siege at the Lindt Chocolat Café.

“I’m just finding out Katrina Dawson was the sister of a prominent barrister Sandy Dawson, who has done some work at Channel Seven, who ...,” Barr said, her voice trailing off.

“Sandy Dawson, who I know and I have friends who know. A mother of three children. I’m just finding that out this morning,” Barr added before bowing her head.

At that point, her co-host, David Koch, stepped in, adding information, allowing Barr to compose herself for the broadcast in Sydney's business and financial district, where the hostage-taking unfolded.

“When you put the faces to the people who have died overnight, it’s just heartbreaking,” Barr said.

The other hostage who died was identified as Tori Johnson, the 34-year-old manager of the Lindt Chocolat Café.

Both Dawson and Johnson were being lauded Tuesday for their courage after unconfirmed reports emerged that they had each taken actions to save their fellow hostages.

There are reports Johnson was shot after he tried to wrestle a shotgun from the hostage-taker, 50-year-old Iranian-born refugee, Man Haron Monis, who himself died after police stormed the café.

Dawson, a lawyer, was said to have been killed in the ensuing firefight as she protected a pregnant friend and colleague, Julie Taylor, whom she had been meeting for a coffee.

Media reports say Dawson died of a heart attack on the way to hospital, but police won't say whether the two died in the crossfire or at the hands of the gunman.

Four people, including a police officer, were wounded in the siege, and two pregnant women were hospitalized as a precaution.

Tearful Australians have been laying mounds of flowers outside the café where two of the 17 hostages were killed.

The gunman, a self-styled cleric with a criminal past, was described by Australian Prime Minister Tony Abbott as a "deeply disturbed person" carrying out a "sick fantasy."

"It's pretty obvious that the perpetrator was a deeply disturbed individual [with] a long history of crime, a long history of mental instability, and infatuation with extremism," he told reporters in Sydney.