Dimitrious "Jimmy" Gargasoulas has been charged with murder in relation to Melbourne's Bourke Street massacre.
He was en route to Melbourne's Magistrates Court on Monday afternoon after being questioned be police.
Friday's rampage left five people dead and at least two still fighting for their lives.
Gargasoulas, 26, had surgery on Saturday for a gunshot wound he sustained when police stopped his alleged deadly drive into lunchtime crowds on Friday. He was released from hospital earlier Monday.
Three adults and two children, a three-month-old baby and 10-year-old, were killed when the accused, who was on bail at the time for assault, allegedly deliberately drove into people in the heart of Melbourne.
Thalia Hakin, 10, Jess Mudie, 22, Matthew Si, 33, a three-month-old baby and a 25-year-old man died.
More than 30 were injured with 13 remaining in hospital on Sunday, at least two of them still fighting for their lives.
"They are critical. They're in a very, very serious condition," Victorian Premier Daniel Andrews told reporters.
"The fear is of course that the death toll from this evil act will rise."
Thousands of Victorians and visitors laid flowers in Bourke St on Sunday as families paid tributes to their loved ones.
The Jewish community in St Kilda East held prayers for Thalia and all the other victims, praying for a speedy recovery for the injured.
Federal MP Michael Danby and local state MP David Southwick were there, telling reporters the community was deeply shocked by the tragedy.
Thalia, whose scout troup were also there to pay respects, should have been returning to Beth Rivkah Ladies College in a few weeks, the MPs said. "I think all Victorians can identify ... with a girl who was going into grade five, her life all in front of her, robbed by some crazed person," Mr Danby said.
Mr Si was a devoted husband and a loving father, brother and son, his wife Melinda said in a statement.
They had just finished lunch together in the city, and parted to go to their respective offices, when he was struck and killed.
"The family would like to thank everyone who helped Matt at the scene and did their best to save him," Ms Si says.
Ms Mudie's family wrote a tribute letter that was released to media: "To our dearest and most badass daughter and sister, Jess. You are always up to do everything and are such bright bubble of joy."
Gargasoulas had been driving erratically around Melbourne after allegedly stabbing his brother, who is also in hospital, much earlier that morning. The accused was well known to police and had been bailed on an assault charge just five days before Friday, when he was due to attend court.
Mr Andrews said bail laws would be reviewed following the attack.
Prime Minister Malcolm Turnbull joined Mr Andrews and laid a wreath at the memorial site on the steps of the old GPO in the mall.
"The loss of fellow Australians in such a shocking, wanton, criminal attack is a tragedy," Mr Turnbull told reporters.
Opposition Leader Bill Shorten said an "evil, murderous hoon" had attacked one of Melbourne's iconic places.
A tax deductible fund has been set up to help the families of victims who died as a result of the attack, with the Victorian and federal governments putting in A$100,000 each.
A public vigil is being planned for Monday night at Federation Square.
- with AAP