A three-month-old baby boy has died following the deadly car rampage that took place in Melbourne's CBD on Friday, bringing the death toll of the attack to five.

Key points: Two children among five people killed in CBD incident

Two children among five people killed in CBD incident Alleged driver Dimitrious Gargasoulas still in hospital and yet to be charged

Alleged driver Dimitrious Gargasoulas still in hospital and yet to be charged Memorial to be set up outside GPO building in Bourke Street Mall

The baby died in hospital on Saturday night, a statement from police said.

It is believed police were in pursuit of a vehicle in the city on Friday when the driver, 26-year-old Dimitrious Gargasoulas, drove erratically around an intersection before speeding down a footpath on Bourke Street and crashing into pedestrians.

Hospitals have treated 37 other people who were injured during the incident, and four victims remain in a critical condition.

Those who died included 10-year-old girl Thalia Hakin, a 25-year-old man, a 33-year-old man, a 32-year-old woman and the three-month-old baby boy who passed away Saturday evening.

The Jewish community is holding a community memorial and prayer service for Thalia tonight.

"Words cannot convey the sorrow we feel for all the victims and their families, and especially for the loss of Thalia and the devastation of her family," said Jennifer Huppert, the president of the Jewish Community Council.

"We would like to thank the first responders, all medical staff involved and all those who came to the aid of the victims."

Government security cabinet meets

The Victorian Government is holding a special meeting of its Security and Emergency Management Cabinet subcommittee today, in response to the tragedy.

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The committee of senior ministers meets at the first opportunity after a major event or disaster.

It is understood the meeting will discuss potential reforms to bail laws, including whether Victoria will continue to use after-hours volunteer bail justices, who are not used in any other state.

The Government has also established a fund for community donations to help families affected by the rampage, contributing $100,000 to the fund, and a vigil has been planned for Monday night at Federation Square.

Meanwhile, federal Opposition Leader Bill Shorten visited the memorial site in the Bourke Street mall this morning to lay a floral tribute in memory of the victims.

"I couldn't be more proud of being a citizen of Melbourne when I see literally thousands of memorials, flowers and teddy bears being laid out in support of these other people who did nothing wrong except for being in the wrong place at the wrong time," he said.

Prime Minister Malcolm Turnbull will also be in Melbourne today to pay his respects to the victims.

Police waiting to charge suspect

Witnesses said there was "no hesitation" as the suspect drove the car into pedestrians, sending "people flying like skittles" and running for their lives.

Gargasoulas remains in hospital under police guard, and is being treated for non-life threatening injuries.

Police were hoping to interview him and charge him later in the weekend.

"Surgery is still occurring. We still haven't been able to be in a position to interview and charge that offender [but] that's still our intention," Victoria Police Chief Commissioner Graham Ashton said on Saturday.

"Through the course of the weekend we will be looking to try and get that opportunity to step in and interview and charge that offender."

It is understood police unsuccessfully attempted to stop him multiple times during the rampage.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 23 seconds 23 s CCTV footage shows pedestrians dodging Melbourne driver

Some members of Victoria Police have hit out at the no-pursuit policy, with one veteran police officer telling the ABC the policy is a "disgrace".

"There was ample opportunity to stop him in the two hours before he reached the city, but the order was not to pursue," the officer said.

Victoria's Homicide Squad will be investigating the incident, with the assistance of the Major Collision Investigation Unit.

Memorial to be set up

Victorian Premier Daniel Andrews said on Saturday a memorial would be set up outside the GPO building in Bourke Street Mall to honour the victims.

"We all need to come together and show our support for victims and family and for everybody who was caught up in this terrible, evil criminal act," he said.

He said the community had been deeply affected by the tragic attack.

"We want answers. We want someone to explain what has gone on," he said.

Bourke Street was re-opened on Saturday morning, after having been cordoned off for most of Friday as police continued their investigations into the incident.