A Lindt Cafe employee calmed gunman Man Haron Monis down so he would not shoot someone in retaliation after three hostages escaped, an inquest into the Sydney siege has been told.

Key points: Employee deceived Monis, allowing hostages escape to go unnoticed

Employee deceived Monis, allowing hostages escape to go unnoticed The 19yo was given "a lot of responsibility" by Monis

The 19yo was given "a lot of responsibility" by Monis Toilet trips were used to discuss possible escape plans

Jarrod Morton-Hoffman told the hearing Monis was "in a state of shock" and thought police had come in and rescued the three escaped hostages.

Mr Morton-Hoffman, who was a 19-year-old student and employee of the cafe at the time, told the inquest he was covering a shift for a colleague on the day of the siege.

He was one of 18 hostages held by Monis during the 17-hour ordeal in December 2014.

The gunman then tried to use remaining hostages as a human shield, following the escape.

"[Monis] was muttering to himself that now he needed to shoot someone in retaliation," Mr Morton-Hoffman told the inquest.

"I wanted to try to stop him thinking police came in so he wouldn't have to shoot someone.

"He was highly emotional, I felt that if I didn't say something at the time he might just pull the trigger."

After Mr Morton-Hoffman calmed Monis down, the gunman said "everyone thank Jarrod — I would have shot somebody".

The worker also slipped cards under the door with hand-drawn maps to help police know the layout of the cafe and where Monis was inside.

The inquest was told by counsel assisting last week that Mr Morton-Hoffman allowed the escape of two further hostages go unnoticed by muffling the sound of their escape, and convincing Monis media reports about the escapes were wrong.

On Tuesday, Mr Morton-Hoffman explained he moved some signage inside the cafe to give the escaping hostages Jieun Bae (also known as April) and Elly Chen "some degree of cover".

He confirmed that while reading media reports for Monis, he told the gunman that the total number of escapees was three, not five as reported, and persuaded Monis that the media were lying.

Mr Morton-Hoffman also said he attempted to bargain with Monis, telling the gunman: "if you let the pregnant lady go, I'll print you a flag."

He said he also concluded that Monis did not really have a bomb in his backpack, as he had claimed, because he so was rough with the bag.

Worker scared if he 'screwed up, someone would have died'

Monis was described by Mr Morton-Hoffman as emotional and "a very dangerous toddler" whose demands would "change with the wind".

The inquest was told hostages placated Monis by pandering to his ideology and criticising then prime minister Tony Abbott — with whom he had requested a live radio debate.

Earlier, Mr Morton-Hoffman told the hearing he was given "a lot of responsibility" by Monis and was scared that "if [he] screwed up someone would have died".

Mr Morton-Hoffman said Monis "freaked out" when he saw police and "pointed his gun at one of the hostages".

In a phone call played to the hearing, the police negotiator asked "how big is the gun?" and Mr Morton-Hoffman responded "[it's a] shotgun ... if you come closer he will shoot and he will explode his bomb".

"He's going to shoot a lady in front of me," Mr Morton-Hoffman is heard saying.

Hostage Louisa Hope could be heard in the background saying "I don't want to die".

Mr Morton-Hoffman earlier said Monis made it the employee's job to accompany people to the toilet and that cafe manager Tori Johnson used a false toilet trip to text message a hostage who had already escaped and who was a fellow staff member, about a side door that was open.

The inquest heard Mr Morton-Hoffman made 10 to 15 trips to the bathroom during which he discussed a possible escape through the side door, and vomited in the bathroom about 8:00pm because he was stressed.

"Monis was becoming more volatile so I wanted longer trips in case he opened fire," the 20-year-old said.

Cafe employee thought RBA was being robbed

Earlier, Mr Morton-Hoffman said he thought the nearby Reserve Bank of Australia was being robbed when Mr Johnson asked him to lock the doors.

The inquest also heard that after Mr Johnson made a triple-0 call, Monis told everyone he had two bombs on him and demanded everyone put their phones and IDs on the table and close their eyes.

Mr Morton-Hoffman said today he did not believe Monis really had bombs across the city.

Mr Morton-Hoffman said Monis did not seem to like Mr Johnson due to his "position of authority" and his "tone was more aggressive" towards the cafe manager.

Monis then forced hostage Ms Hope to make calls to the media and called her his "secretary", Mr Morton-Hoffman said.

Mr Morton-Hoffman said also he made media calls but Monis then removed Mr Morton-Hoffman from making calls after a radio announcer described him as "calm".

"[Monis said] the media would respond better to someone who was crying [on the phone]," Mr Morton-Hoffman told the inquest.

Towards the end of the siege, Mr Morton-Hoffman led the escape of six hostages — including himself — from the cafe as Monis fired a shot after them.

Shortly after, Monis shot dead cafe manager Mr Johnson, prompting the storming of the Lindt Cafe by Tactical Operation Unit (TOU) officers, killing Monis and ending the siege.

The final stage of the inquest, which has been described by the coroner as one of the most complex in Australia with implications for national security, is looking at what happened during the siege itself and the police response to it.

The coroner started hearing evidence in May 2015 and is expected to hand down his findings later this year.