Sydney hostage crisis in pictures: Australia mourns with sea of flowers at site of Martin Place terror attack

'Our laid-back nature has just changed'

Sydneysiders visit the floral memorial for victims Tori Johnson and Katrina Dawson at the scene of the Martin Place siege in the CBD in Sydney (Rex)

Tearful Sydney residents led Australian tributes today at the site where a gunman and two hostages were shot dead following a 16-hour siege at a popular cafe.

The deadlock was broken in the small hours of Monday night with a barrage of gunfire that has rocked a nation which prides itself on peace to its core.

Prime Minister Tony Abbott joined the outpouring of national mourning and laid a bouquet at Martin Place. The plaza in Sydney's financial and shopping district where the crisis occurred that has since become the site of a makeshift memorial.

"I'll never forget this day as long as I live," said Jenny Borovina, who was in tears with two friends carrying white flowers to the site. The effect of the standoff would leave a permanent scar on Australia's psyche, she predicted. "Our laid-back nature has just changed."

Flowers are placed by people as a mark of respect for the victims of Martin Place siege in Sydney

Grieving Lindt cafe workers lay flowers at the scene of the Martin Place siege, which claimed their manager Tori Johnson, in the CBD in Sydney

People join hands as they mourn near the Lindt chocolate cafe in Martin Place

Like so many who work in the area, Borovina said she was locked down in her office near the cafe for more than four hours Monday before police gave her the all-clear to leave. During that time, she said, she called her son to say take care. She also called her aunt, asking her to look after her son if she didn't make it out alive.

"Australia was a really safe place before," said Andrea Wang, who laid a bouquet of lilies at the site, near her office.

Premier Mike Baird visits the floral memorial for victims Tori Johnson and Katrina Dawson at the scene of the Martin Place siege in the CBD in Sydney

Women embrace in Martin Place in Sydney

A woman places flowers as a mark of respect for the victims of Martin Place siege in Sydney

"I hope our country gets through this very quickly," she said, adding that her family from China had been calling. "They worry about me in this country."

The gunman has been identified as 50-year-old Man Haron Monis, who Mr Abbott said had "a long history of violent crime, infatuation with extremism and mental instability."

People lay flowers at a floral memorial at the scene of Sydney's siege (GETTY)

Others pray near the site of the dramatic siege

Flowers are left as a sign of respect at Martin Place in Sydney

Abbott said Monis was "a deeply disturbed individual" known to the police but that he was not on a terror watch list at the time of yesterday's attack.

One of the victims was identified as 38-year-old Katrina Dawson, a Sydney lawyer and mother of three children.

Police officers visit the floral memorial for victims Tori Johnson and Katrina Dawson at the scene of the Martin Place siege in the CBD in Sydney

Australian Prime Minister Tony Abbott and his wife Margie prepare to place floral tributes near the cafe in central Sydney

Australian Prime Minister Tony Abbott and his wife Margie pay their respect to the victims of the siege in Martin Place in Sydney central business district

"Katrina was one of our best and brightest barristers who will be greatly missed by her colleagues and friends" Jane Needham, president of the New South Wales Bar Association, said in a statement.

The other victim was named in Australian media as the 34-year-old manager of the cafe, Tori Johnson.

Flowers lay at a memorial near the Lindt chocolate cafe in Martin Place following a dramatic siege in Sydney

"It's shocking that it has happened to people like us that are just going out for a coffee," said Michael Gardiner, a visitor from the western city of Perth, who recalled sitting in the cafe about a year ago. "But it's beautiful to see everyone coming here. There's a real sense of community."

Katrina Dawson, a 38-year-old barrister and mother-of-two who worked in Sydney's central business district was named locally as one of the victims (EPA)

Tori Johnson, the manager of the Lindt Chocolate Cafe, Sydney, who was killed during the siege (Lindt Chocolate Cafe Australia)

National flags were lowered to half-staff on the landmark Harbour Bridge as Australians awakened to the surreal conclusion of the crisis. The state's premier expressed disbelief that the attack could happen in Australia — a place he dubbed "a peaceful, harmonious society which is the envy of the world."

"There is nothing more Australian than dropping in at the local cafe for a morning coffee," said Abbott, the prime minister. "And it's tragic beyond words that people going about their everyday business should have been caught up in such a horrific incident."

Additional reporting by The Associated Press