The 18-year-old Muslim extremist who was shot dead by police after he stabbed two officers may not have been acting alone, Victoria's police commissioner has said.

In an interview with Melbourne radio station 774 this morning, Commissioner Ken Lay said there was evidence suggesting Numan Haider had discussions with other people prior to the stabbing.

“There’s some information that he was certainly talking to other people around the time,” Mr Lay said. 'It's certainly something we're pushing.'

"Having said that, there were some really worrying pieces about this young man's behaviour that we are working through.

Mr Lay also denied claims Haider - who had been carrying two knives - had been been planning a beheading.

'There is nothing, absolutely nothing to suggest that was the intention,' he said.

Haider - who was killed outside Endeavour Hills police station in suburban Melbourne on Tuesday evening - was known to police and had been under investigation for his radical views for at least three months.

But police had not considered Haider to be an imminent threat. Officers had visited his house and spoken to his parents about his behaviour, according to reports, and the officers offered to shake hands in the seconds before he launched the attack.

The final trigger for the attack was a visit by police officers to the family home, according to an account by firebrand cleric Mohammed Junaid Thorne, who claims to have know Haider.

Haider was sitting with friends at a Hungry Jack's fast food restaurant when his parents called him and told him police had just visited their home and searched his room, Thorne said.

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Numan Haider was reportedly researching if the prime minister had any upcoming trips to Melbourne

He was also said to be planning a trip to Iraq and Syria

The 18-year-old was shot outside Endeavour Hills police station on Tuesday night. His body was removed on Wednesday

Haider was shot once after he stabbed two police officers from the counter terrorism unit

This enraged Haider, who called police and had an argument on the phone while complaining his privacy had been invaded, according to Thorne's account. It was during this call that it was arranged for Haider to come to the Endeavour Hills police station to meet police.

Police reportedly confirmed they had visited the house in the hours before the attack but said they only spoke to Haider's parents and did not search his room.

The attack was the culmination of what appears to be an extraordinary transformation from an average young Muslim man to a bloodthirsty extremist.

Haider was training as an electrician at Chisholm Institute of TAFE after recently completing Year 12 at Lyndale Secondary College in Dandenong, according to a work history posted online.

He was recently employed stacking shelves at a Coles supermarket, where he learned about 'working in a team ... and following instructions.'

Prior to that, he had worked at the local Dandenong fruit store, spruiking and completely general duties such as sweeping up and assisting customers.

Haider began adopting more radical views after attending the al-Furqan centre in Springavle. The centre was at the centre of counterterrorism raids in 2012.

Police said Haider first came to their notice three months ago. The Australian reported police were called to a disturbance at a shopping centre in Narre Warren on 25 July involving a group of young Muslim men who were loudly debating Islam and matyrdom.

Haider was one of them, and security agencies began monitoring him. Last Friday, Haider was stopped by police as he walked through Dandenong Mall waving an Islamic State flag. He had posted anti-police messages on Facebook.

The ABC reported that Haider had been making inquiries about Mr Abbott's movements, taking particular interest in his plans to travel to Melbourne in coming months.

Mr Abbott was on Wednesday night in New York, where spoke with other world leaders at the United Nations about global security and the terror threat posed by Islamic State.

In Melbourne, a family friend posted a tribute to the boy on her Facebook page, emphasising that he was just a 'teenager'.

She remembered how he used to help his mother with the housework and said: 'I'll never forget that smile on your face no matter how much I used to tell you and my brother off for going into mischief'.

Another young man who knew the teenager described him as a calm and gentle person, and said he had never seen any indications that Haider was involved with any radical groups.

Mohamed Ibrahim - who shared a room with the 18-year-old at a Mulsim youth camp last year - told the ABC's PM program: 'He was a gentle, soft spoken young boy and when I heard the report yesterday about a man who had been shot - when I actually found out he was Numan - I was absolutely shocked.'

'There were no hints that he was part of a group, there were no signs that he was someone we should be worried about,' Mr Ibrahim said.

The friend also revealed he was stunned at how much the teenager had changed.

'I think him, from going to being an inquisitive young lad to being someone who was drawn towards these kind of ideas, it's something we need to take seriously,' Mr Ibrahim said.

People were seen coming and going from the Haider's family home on Wednesday

The body was taken away by the coroner on Wednesday

Many mourners visited the Melbourne property on Wednesday

Pictures from a helicopter show a man's body lying in a car park where the confrontation occurred

The Herald Sun reported that Haider had spent the past few weeks distraught after a recent split from his wife - who had converted to Islam.

'It (the divorce) was a huge factor in his life. They were living apart. He was very upset,' a friend told the website.

The friend added that Haider was also distressed about having his passport cancelled and being monitored by police.

In a Facebook post, Thorne claimed Haider had his passport cancelled without cause and police were at his house before he was shot outside Endeavour Hills police station on Tuesday evening.

'We understand that the local authorities had canceled the passport of this young boy for no reason, keeping him a captive in his own country for no valid purpose.

'We also understand that the police visited or raided his house (not clear yet) as he was hanging out with some friends in Hungry Jacks, just hours before his death,' Thorne wrote on Wednesday afternoon.

The controversial preacher also said that the teenager was 'provoked' and the Australian government has an agenda to create division in the community.

' This boy was not a casualty of an armed heist, nor was his death the result of some drug deal that went wrong, rather he was killed by the same people who are supposed to be protecting this country.

Police carried bags of evidence away from the crime scene

Forensic police at the scene in Melbourne where an 18-year-old man was shot dead by police after allegedly stabbing two officers

The stabbing took place outside Endeavour Hills police station, south-east of Melbourne, at about 7.45pm on Tuesday night

'We still ask and wonder, why deadly force was immediately used against a teenager, who was provoked in the first place and forced in to such a situation.

'The Abbot (sic) government has succeeded in creating division amongst our community based on religion,' Thorne posted.

He also said the stabbed teenager was a 'wonderful, practicing (sic) young brother' – and described incident as 'murder'.

'It is a time of grief for us Muslims,' Thorne told Daily Mail Australia earlier on Wednesday.

According to the Herald Sun, the teenager had been seen handing out brochures at nearby Dandenong Shopping Plaza, trying to convert others to Islam.

He was apparently seen there with four others last Thursday, wearing camouflage pants while holding a black and white flag.

Haider's parents pleaded with their son to stay home the night he was killed, the ABC reported.

They were apparently concerned for his safety, but despite this he went to meet police - who he called when he was outside the station as he did not want to meet them inside.

Police said they believed the man was attending the police station for an 'amicable discussion' when he attacked without warning

The officers - one from the Australian Federal Police and the other from Victorian Police - were stabbed after the teenager drew a knife during an arranged meeting

The AFP officer was reportedly stabbed in the face and upper body, while the Victorian police officer was stabbed in the arm

Assistant Police Commissioner Luke Cornelius (left) said police had no choice but to shoot the teenager

On Tuesday night, Victoria Police Assistant Commissioner Luke Cornelius said: 'Our members had no inkling this individual posed a threat to them and as far as we were concerned it was going to be an amicable discussion about that individual's behaviour,'

'It is also clear to us that (the) individual has, without any warning, produced a knife and assailed them with a knife,' he said. 'It's absolutely clear to us our members had no choice but to act in the way they did.'

Victoria Police Commissioner Ken Lay told reporters the AFP officer, aged 43, suffered multiple stab wounds to his face, neck and abdomen. He underwent surgery and was in a serious but stable condition in hospital. He has a wife and two children.

Witnesses told the Sydney Morning Herald on Tuesday night Haider had been yelling insults about Prime Minister Tony Abbott and the Australian government.

The bomb squad examined the man's car and the police station following the incident.

Last night, police said they believe the man was 'acting on his own' but could not comment on his motivations.

Mr Cornelius said the Victorian officer fired the single shot that killed the man.

The bomb squad examined the man's car and the police station following the incident

Suited up: Bomb squad officers, pictured after the incident.

Much of Heatherton Rd - where the shooting took place - was closed in the aftermath of the attack

Neighbours of the Haider family said they were shocked by the incident.

'Nowadays you have to be suspicious about every person, you never really know,' a neighbour, who did not wished to be named, told Daily Mail Australia.

'You never know what's happening across the road.'

He said it was a multicultural neighbourhood.

'We've got a good mix of people around here. There are Greeks here, we've got Italians over there...and some other countries,' the neighbour said.

Islamic Council of Victoria secretary Ghaith Krayem said Haider had been involved with Al-Furqan, an Islamic fundamentalist group raided by police in 2012, but had not had recent contact with them.

Officers said there is information suggesting the man who was shot had previously displayed an ISIS flag

The man was a person of interest to police and part of an ongoing investigation

The altercation took place about 7.45pm and homicide detectives are leading the investigation

Mr Krayem said the threat of ISIS in Australia had been overplayed and police were on top of potential terror threats in Melbourne.

'There's nobody who I'm aware of in the last couple of months in terms of who the police are looking at, who the police weren't already looking at well before now,' he said.

Justice Minister Michael Keenan urged Australians to remain calm.

'We need to go about our daily lives,' he said. 'It is this type of bravery and dedication shown by these officers that will continue to keep our community safe and secure.

'I want to make it clear that the public should feel confident that the police, the security services and the government are taking every possible step to ensure their safety and security of all our communities.'

The Islamic Council of Victoria has called for an investigation into the incident.

'There needs to be a full and objective investigation into this incident to ensure that such a tragedy is never repeated,' the council said in a statement on Wednesday.

'This tragedy highlights the real cost of a failure to deal with these serious issues and why we have made numerous calls on the Australian government to deal with the root causes of alienation and disaffection of people such as this.'

The council said it would provide support to the man's family.

The shooting took place near Endeavour Hills station after two police officers were stabbed

Heatherton Road where the station is located was sealed off while investigations continued

Prime Minister Tony Abbott was on his way to a UN meeting on global security issues when the Melbourne attack occurred

On Monday, Abu Mohammad al-Adnani, the official spokesman of the Islamic State terror group purportedly issued a chilling message calling on his followers to murder Australians in ghastly ways.

Al-Adnani said: 'If you can kill a disbelieving American or European – especially the spiteful and filthy French – or an Australian, or a Canadian, or any other disbeliever from the disbelievers waging war, including the citizens of the countries that entered into a coalition against the Islamic State, then rely upon Allah, and kill him in any manner or way however it may be.'

The country witnessed the largest counter-terrorism raids in Australian history last week. More than 800 police officers were involved in Sydney alone.

Police allege the effort disrupted a plot to behead a random member of the public. Omarjan Azari, 22, was charged with conspiracy to commit a terrorist attack on Australian soil.

A second man, a 24-year-old from Merrylands in Sydney's west, was charged with possessing ammunition without license and unauthorised possession of a prohibited weapon.

The man, Ahmad Rahmany, was fined $500 and handed a good behaviour bond after pleading guilty to the charges on Wednesday in Fairfield Local Court.

On Monday evening footage emerged of the spokesman for the Islamic State terror group threatening nations around the world, including Australia