Sydney (CNN) Only one of the Sydney siege victims was shot by the gunman, with the second killed by fragments of police bullets fired when officers stormed the cafe, an inquest has heard.

The revelations, which came in the opening day of an inquest into the 16-hour siege of a central Sydney cafe, are likely to further fuel questions about how New South Wales Police responded to the December 15 incident, especially their choice of weapons.

Of the five shots fired by Man Haron Monis , a self-styled Muslim cleric who took 18 people hostage, only one found a target, counsel assisting the coroner Jeremy Gormly told the inquest.

Monis shot and killed cafe manager Tori Johnson execution-style, prompting police to storm the cafe in the early hours of December 16, Gormly said.

All the injuries that followed -- two fatal, including those to Monis, and four non-fatal -- were caused by police fire, according to the evidence.

Police response adequate?

The inquest is expected to examine whether the deaths of Johnson, the cafe's 34-year-old manager, and Katrina Dawson, a 38-year-old lawyer, could have been prevented.

Addressing those at the hearing, which was closed to the public but open to hostages and victims' families, Gormly outlined the events that led to the deaths of Johnson, Dawson and the gunman.

Photos: Photos: Sydney cafe siege Photos: Photos: Sydney cafe siege Sydney cafe siege – A message of condolence is written on the pavement at Martin Place, Sydney on Wednesday, December 17. #illridewithyou became a trending hashtag on Twitter during the siege, expressing solidarity with Australian Muslims in the wake of deadly siege at the Lindt Cafe in Sydney. Hide Caption 1 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – A woman walks past flowers placed by people as a mark of respect for the victims of Martin Place siege on Tuesday, December 16. Hide Caption 2 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Members of the Muslim community show their respect at Martin Place on December 16. Hide Caption 3 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Prime Minister Tony Abbott arrives with his wife Margaret to pay their respects at Martin Place on December 16. Hide Caption 4 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Australian flags fly at half mast on Sydney Harbour Bridge on December 16 following the fatal siege. Hide Caption 5 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – An injured hostage is carried to an ambulance from a cafe in Sydney on December 16. Gunfire erupted early Tuesday as police stormed the Lindt Chocolate Cafe, where a gunman had been holding hostages since Monday morning. Hide Caption 6 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Hostages run toward police officers on December 16. Hide Caption 7 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – A police officer and a paramedic escort a hostage away from the scene of the siege on December 16. Hide Caption 8 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – An injured hostage is wheeled to an ambulance after shots were fired during the raid on the cafe. Hide Caption 9 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Two armed police officers stand ready to enter the cafe on December 16. Hide Caption 10 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – A hostage stands by the front entrance of the cafe as she turns off the lights on Monday, December 15. Hide Caption 11 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – A hostage runs toward police on December 15. She was one of five people seen fleeing the cafe. Hide Caption 12 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Police gather near the cafe on December 15. Hide Caption 13 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Hostages behind the cafe's window hold up a black flag with Arabic script on December 15. Hide Caption 14 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – A police officer listens to a radio on December 15. Hide Caption 15 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Two hostages make it to safety outside the cafe on December 15. Hide Caption 16 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – A police sniper walks to his vehicle on December 15. Hide Caption 17 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – A journalist reports on the situation in Sydney. Hide Caption 18 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Armed police are seen outside the cafe on December 15. Hide Caption 19 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – People rush past armed police near the cafe on December 15. Hide Caption 20 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Police close a street near the scene on December 15. Hide Caption 21 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Police officers talk at the scene on December 15. Hide Caption 22 of 23 Photos: Photos: Sydney cafe siege Sydney cafe siege – Armed police patrol near the Sydney Opera House. Major landmarks in Sydney were evacuated as police responded to the hostage situation. Hide Caption 23 of 23

He said the first killing, of Johnson, occurred at about 2.14 a.m. -- shortly after a group of hostages fled the cafe.

Gormly described an execution-style killing, in which Monis ordered Johnson to kneel, then "simply shot him, without further notice or warning, in the back of the head."

"The end of the barrel was about 75 centimeters from Mr Johnson's head at the moment of discharge," he said. "Mr Johnson is believed to have died immediately."

Flashes and bangs

The killing was witnessed by a police marksman, resulting in an immediate order to force entry, he said.

Police then shot out the glass doors and windows, threw in 11 "distractors," producing flashes and bangs, and two armed tactical response officers entered, firing 22 shots.

At least two police bullets or bullet fragments struck Monis in the head and 11 other police bullets or fragments hit his body, killing him instantly, said Gormly.

But their rounds ricocheted off the hard surfaces in the cafe, killing Dawson and injuring three other hostages and one of the response team, who was struck in the face.

"Ms Dawson was struck by six fragments of a police bullet or bullets," he said.

Cake and tea

Gormly said the siege began after Monis entered the Lindt Cafe at about 8.33 a.m., carrying a large backpack and a plastic bag containing a sawn-off shotgun, and ordered chocolate cake and tea.

He moved to a table with a clear view of the cafe, then, after about 30 minutes, asked to speak with the manager.

Staff noticed that Johnson's body language appeared tense. He called on an employee to fetch his keys, lock the doors and remain calm.

Monis then stood up, produced a shotgun and announced that he had a bomb, before ordering hostages to hold up an Islamic flag.

He then ordered Johnson to make an emergency call to authorities announcing that it was a terrorist attack, and that there were bombs elsewhere.

Police arrived at the scene shortly after.

Seeking answers

Several investigations into what occurred over the two days of the siege are underway, including what information security agencies had on Monis, and how the police handled the crisis.

Lawyers representing Dawson, Johnson and the police force will appear at the inquest, as well as lawyers representing two tactical response officers.

Johnson's family members were in attendance, as well as John O'Brien, one of the first hostages to escape.