The family of a man shot dead by police in Brisbane's CBD on Sunday says he had been suffering from schizophrenia for the last three years and didn't receive enough support.

Key points: Police shot the man dead after he attacked two tourists with a knife

Police shot the man dead after he attacked two tourists with a knife The man's family say he suffered from schizophrenia and needed more support

The man's family say he suffered from schizophrenia and needed more support Police confirmed there was nothing to suggest the incident was linked to terrorism

Mohammad Ikraam Bahram, 24, drove into the city armed with two knives before attacking two UK tourists, stabbing a 26-year-old man in the back.

His sister told the ABC their family — from Logan south of Brisbane — was shocked by the news and didn't know what triggered Mr Bahram to go into the city armed.

"He was an absolutely amazing person, you'll never meet anyone like him," she said.

"He would give you the shirt off his back — that's how much of a kind person he was."

She said the family believed there was not enough support offered to help Mr Bahram, who they say had been diagnosed with schizophrenia.

Police outside the Westin Hotel in the Brisbane CBD, after the shooting. ( ABC News: Lexy Hamilton-Smith )

Mr Bahram's family said had been hospitalised at least four times in the last three years due to his illness and was most recently admitted to the Princess Alexandra Hospital in December.

Queensland Health said it could not confirm whether the 24-year-old was being treated in hospital before the incident on Sunday, due to the ongoing coronial investigation.

The family said they are angry and believe Queensland Health failed their son.

"He has been in mental health getting help," his sister said.

"He didn't get enough support.

"There are families hurting from this, it's absolutely heartbreaking."

The forensic scene where police shot and killed a man outside the Westin Hotel on Mary Street. ( AAP: Glenn Hunt )

Health teams 'do their best', minister says

Health Minister Steven Miles avoided speaking about Mr Bahram's case but said the care provided to him by Queensland Health would be investigated.

"I am not going to pre-empt any [investigation] but I am going to say that every day our mental health teams do their very best to take care of some of the most difficult consumers," he said.

""I'm not at liberty to outline any private patient information. We will cooperate with any investigation.

"Mental health issues are very complex and what we can do as a health service is ensure we have the resources and staffing to support people and we are doing that.

"Across the state we are investing in mental health facilities."

'Unacceptable delays' in mental health care: AMA

Dr Richard Kidd from the Australian Medical Association (AMA) said Mr Bahram's experience highlighted "major shortcomings" in the way mental health treatment was funded and structured.

"There is really strong evidence if you invest in good quality, well-resourced mental health outreach support, you are going to, in many cases, prevent this kind of tragedy," he said.

"For many years now, the AMA and many other bodies have been calling for a much greater investment in mental health.

"The State Government and Federal Government have been missing in action when it comes to mental health for a long time and it's just not good enough.

"It's causing unacceptable delays to care.

"We really need to invest more funding in a smart way into mental health and outreach support.

"If we do that, we will be a more humane society and prevent suffering and harm for not only individuals with mental health challenges but also for those around them."

Queensland Health Minister Steven Miles said the care provided to Mr Bahram would be investigated. ( AAP: Darren England )

Family furious over terrorism claims

The Brisbane Islamic community and Mr Bahram's family have also been angered by some reports that the attack may have been motivated by terrorism.

His family said Mr Bahram was born in Sydney after his mother moved to Australia from Afghanistan as a refugee.

"The worst thing was when we turned on the TV and saw reports stating he was a terrorist. That is disgusting behaviour, absolutely disgusting," his sister said.

"He is not related to any terrorist groups or anything like that.

"We are just a normal Aussie family who have had our brother — my parent's son — taken away."

Police confirmed there was nothing to suggest the incident was linked to terrorism.

Islamic Council of Queensland secretary Muhammad Khatree says the council has requested a meeting with Police Commissioner Katarina Carroll following the shooting. ( ABC News: Anna Hartley )

Islamic Council of Queensland secretary Muhammad Khatree said misinformation was damaging, not only to the man's family, but to relations between the Islamic community and police.

"Any reports that try to force a connection to terrorism are highly irresponsible," Mr Khatree said.

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"We have been informed by family members that the deceased was born in Australia and suffering from grappling with severe mental health issues.

"We are also seriously concerned by the excessive force used by police officers."

"To have his life taken away like this is unjust," his sister added.

"The police have gone about this the wrong way. They could have used tasers.

"It was excessive [force]."

As of Tuesday morning, Mr Bahram's family said they were still waiting for investigators to release their son's body.

Police defend officer's actions amid investigation

The use of deadly force will be investigated by Queensland police's internal ethical standards command but, in an unprecedented move, QPS Commissioner Katarina Carroll has publicly supported the officers involved.

"Every day my officers go to work to protect Queenslanders," she posted on Instagram.

"Two of our first responders faced a critical situation that, as police, we hope we are never confronted with.

"I stand with them."

Queensland Police Union president Ian Leavers also stood by the action of the officers.

Queensland Police Union president Ian Leavers says police acted 'with restraint' and were doing their job when they shot and killed 24-year-old Mohammad Akram Bahram in Brisbane on Sunday. ( ABC News: Anna Hartley )

"A taser is not appropriate because if both prongs do not connect, what you have is a murdered police officer," he said.

"Sadly, an offender made a decision to threaten the lives of others and a police officer, and the police did their job."

The UK tourist who was stabbed in the incident received a single stitch in hospital and was discharged.

Both the man and the 25-year-old woman have been interviewed as part of the coronial investigation.