Police say a man who allegedly mowed down 19 pedestrians, critically injuring three during peak-hour crowds in Melbourne’s CBD, has blamed “the mistreatment of Muslims” for his actions.

Speaking on ABC News Breakfast on Friday, Victoria Police acting commissioner Shane Patton said the driver, a 32-year-old Australian man of Afghan descent, was spoken to on Thursday night where he “made some utterances”.

“Last night investigators gained some access to him and were able to not conduct a formal interview, but had some preliminary discussions with him.

“He spoke of dreams and voices, but also attributed some of his activities as well due to the mistreatment of Muslims.”

Search warrants at West Heidelberg and Oak Park were also conducted on Thursday night. Family members were present and assisted police, but none was taken into custody.

The accused, who came to Australia through official channels under a refugee program, remains in hospital under police guard. He is due for a psychiatric assessment before police interview him later on Friday.

“We haven’t ruled anything in or out and our counter-terrorism command continues to obviously assist Crime Command in this investigation,” he said.

On Friday afternoon, Minister for Home Affairs Peter Dutton said while Victoria Police had not specifically established a terrorism link in the incident, he was not ruling it out.

“If you look at the circumstances, where people have been mowed down by this person in the car, that is a very serious circumstance, and so in light of that, and obviously all of our CT [counter-terrorism] officers within the Australian Federal Police, officers within ASIO, the Australian Border Force, all of them are working very closely to look at every aspect, every detail of this case with the Victorian police at the moment,” Mr Dutton said.

“And so I don’t want to pre-empt anything, but we are certainly not ruling out a terrorist link and we certainly aren’t drawing any conclusions at this stage.”

An 83-year-old man remains in a critical condition in hospital, a four-year-old boy was transported to the Royal Children’s Hospital with head injuries, nine foreign nationals and a New Zealand citizen were injured.

His comments come as Prime Minister Malcolm Turnbull described the 4.40pm rampage on Flinders Street as a “despicable and cowardly act”.

The rampage comes 11 months after six people were killed and 30 injured in a similar incident just four blocks away in Bourke Street.

Fairfax report the alleged driver, who police say had a history of mental illness and ice addiction, as Saeed Noori.

Acting commissioner Patton praised a “heroic” off-duty police officer, who tackled and arrested the driver despite potential danger.

The officer was injured in the encounter and required surgery on an injured finger on Friday morning.

Victorian Premier Daniel Andrews said on Thursday it “would be right to single [the officer] out for special praise”.

“He instinctively came to the aid of others, in the protection of public order, and potentially, avoiding so much other carnage,” Mr Andrews said.

One witness said a white Suzuki SUV, reportedly owned by a family member, was travelling at up to 100 km/h as it hit the pre-Christmas crowd of shoppers near the corner of Flinders and Elizabeth Streets before crashing into the tram stop.

The alleged driver had been charged with traffic offences over recent months. He was also known to police in relation to a minor assault from around 2010.

The driver was the only person in the vehicle, and no weapons were seen in the SUV.

Watch footage of an arrest

Dozens of witnesses were transported by bus to the Victoria Police Centre in Melbourne’s nearby Docklands area for interviews.

One caller to ABC radio, who identified himself only as John, said as he was crossing Flinders Street when he saw the SUV out of the corner of his eye “coming at high speed”.

John said he saw “bodies flying through the air”. The car then slammed into a tram stop and people dragged the driver from the vehicle, he said.

Another caller, David, told ABC he estimated the car to be travelling between 60 km/h and 100 km/h when it drove through a throng of 40 to 60 people.

“It was over in a flash. I heard the rev of the engine then heard the first thump … then I saw it plough through the crowds … bodies were sent flying,” he said.

Scene on Flinders St. White SUV has gone through pedestrians and crashed into tram stop @9NewsMelb pic.twitter.com/dDYYVFCpMW

— Andrew Lund (@andrew_lund) December 21, 2017

David said he saw around six to eight people lying on the ground, two he could see were “conscious and breathing” while another two appeared unconscious but bearing no obvious injuries.

Sri Maradari, who works at Rocket Burger on the corner of Flinders and Exhibition Street, looked on as he saw what he estimated to be 10 to 15 people being treated by paramedics.

“We were busy in the kitchen. We heard some noise and we came out to look,” he told The New Daily. “It was really loud. A car hit people. Everyone starting shouting.”

Passerby Tookta Stiles told The New Daily she was leaving a meal with friends at a nearby Vietnamese restaurant amid the chaos.

Ms Stiles said she comforted a woman who was crying and in shock.

The woman said she had been crossing the road at Flinders Street when “a car came out of nowhere” and nearly hit her, Ms Stiles said.

“I saw the lady panicking and crying so I tried to give her comfort,” she said.

“She told me she was about to cross the road and the guy came from nowhere and sped up at the traffic lights. She was about to cross the road at Elizabeth Street and the guy behind her was [hit]. She tried to run and the car just missed her. She was in shock.”

ABC coverage of the incident

Premier assures public Victoria is safe

Premier Daniel Andrews described the incident as “an act of evil, an act of cowardice” at a press conference on Thursday evening.

He assured the public that police would be a visible presence over the festive period so that people could safely enjoy the Boxing Day Test and Carols by Candlelight on Christmas Eve at the Myer Music Bowl.

The Victorian government has already put in measures such as temporary concrete bollards and loudspeakers in the CBD following January’s Bourke Street massacre that killed six people.

Mr Andrews said it would be impossible to fully protect some features of Melbourne from “terrible, horrific, one-off events like this” without changing the “nature of the city for everybody forever”.

However, he said there would be “proper inquiries” and a “full review” into Thursday’s attack and his government would make any changes needed.