SYDNEY, Australia (AP) — The deadly siege began in the most incongruous of ways, on a sunny Monday morning (Australia time) inside a cheerful cafe in the heart of Australia’s largest city. An Iranian-born gunman burst in, took 17 workers and customers hostage, and forced some to hold a flag with an Islamic declaration of faith above the shop window’s festive inscription of “Merry Christmas”.

It ended after midnight with a barrage of gunfire that left two hostages and the gunman dead, four others wounded, and a nation that has long prided itself on its peace rocked to its core.

After waiting 16 hours, police decided to storm the Lindt Chocolat Cafe early Tuesday after they heard a number of gunshots from inside, said New South Wales state police Commissioner Andrew Scipione.

A loud bang rang out, several hostages ran from the building and police swooped in amid heavy gunfire, shouts and flashes. A police bomb disposal robot also was sent into the building, but no explosives were found.

“They made the call because they believed that at that time, if they didn’t enter, there would have been many more lives lost,” Scipione said.

The gunman was identified as Man Haron Monis, who once was prosecuted for sending offensive letters to families of Australian troops killed in Afghanistan.

Scipione wouldn’t say whether the two hostages who were killed — a 34-year-old man and a 38-year-old woman — were caught in crossfire, or shot by their captor. Among the four wounded was a police officer shot in the face.

“Until we were involved in this emergency action, we believed that no one had been injured. That changed. We changed our tactic,” he said.

An investigation into the incident was under way.

Officials rolled one gurney out of the cafe carrying what appeared to be a man draped in a blood-soaked sheet with a bloody handprint in the centre. Paramedics also carried away a woman with blood-covered feet.

“I can only imagine the terror that they’ve been through,” Scipione said. “They are very brave people who in many cases were just buying a cup of coffee and they got caught up in this dreadful affair. We should reflect on their courage.”

Local media identified the gunman as 50-year-old Monis, and a police official confirmed his identity. Under department rules, officials do not identify themselves unless speaking at a formal news conference.

While Monis’ motivation for the attack was still unclear, he is no stranger to police or Australia’s justice system.

Last year, he was convicted and sentenced to 300 hours of community service for using the postal service to send what a judge called “grossly offensive” letters to families of soldiers killed in Afghanistan between 2007 and 2009.

At the time, Monis said his letters were “flowers of advice,” adding: “Always, I stand behind my beliefs.”

He later was charged with being an accessory to the murder of his ex-wife. Earlier this year, he was charged with the sexual assault of a woman in 2002. He has been out on bail on the charges.

“This is a one-off random individual. It’s not a concerted terrorism event or act. It’s a damaged-goods individual who’s done something outrageous,” his former lawyer, Manny Conditsis, told Australian Broadcasting Corp.

“His ideology is just so strong and so powerful that it clouds his vision for common sense and objectiveness,” Conditsis said.

Australians were just waking up to the surreal conclusion of the crisis as 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 .”

“In the past 24 hours, this city has been shaken by a tragedy that none of us could have ever imagined,” Premier Mike Baird said. “The values we held dear yesterday we hold dear today. They are the values of freedom, democracy, and harmony. These defined us yesterday, they will define us today, they will define us tomorrow.”

Hundreds of police flooded the city. Streets were closed and offices evacuated. The public was told to stay away from Martin Place, site of the state premier’s office, the Reserve Bank of Australia, and the headquarters of two of the nation’s largest banks. The state parliament house is a few blocks away, and the famous Sydney Opera House also is nearby.

Throughout the day, several people were seen with their arms in the air and hands pressed against the window of the cafe, with two people holding up a black flag with the Shahada, or Islamic declaration of faith, written on it.

The Shahada translates as “There is no god but God and Muhammad is his messenger.” It is considered the first of Islam’s five pillars of faith, and is similar to the Lord’s Prayer in Christianity. It is pervasive throughout Islamic culture, including the green flag of Saudi Arabia. Jihadis have used the Shahada in their own black flag.

Australian Muslim groups condemned the hostage-taking in a joint statement and said the flag’s inscription was a “testimony of faith that has been misappropriated by misguided individuals.”

In a show of solidarity, many Australians offered on Twitter to accompany people dressed in Muslim clothes who were afraid of a backlash from the cafe siege. The hashtag #IllRideWithYou was used more than 90,000 times by late Monday evening.