Fourth person dead in Melbourne's CBD car rampage

A 33-year-old man died in hospital late on Friday night after a 10-year-old girl, 32-year-old woman and 25-year-old man died on the scene after Dimitrious Gargasoulas drove his car into the pedestrian-only section of the Bourke Street shopping mall early on Friday afternoon, ploughing into pedestrians.

Police confirmed that Gargasoulas, 26, was shot in the arm before he was arrested on Bourke Street.

Graham Ashton, chief commissioner of Victoria Police, said Gargasoulas remained in hospital under police guard on Saturday morning and police were hoping to interview and formally charge him over 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," Ashton told reporters 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," added Ashton.

Ashton confirmed that Gargasoulas was out on bail after being charged with family violence related offenses.

Police will allege that Gargasoulas stabbed his brother, who remains in a serious condition in hospital, in the south-east suburb of Windsor at 2am local time on Friday morning before stealing the car that he used to mow down pedestrians in the city on Friday afternoon.

More than 30 people were injured in the incident and taken to hospitals across Melbourne with five remaining in a critical condition.

Andrew Crisp, deputy police chief commissioner, praised Melburnians for their action during the incident.

"I don't know really how to put it into words, what people must have been thinking and feeling as this vehicle was travelling at high speed along Bourke Street... it's extremely traumatic," Crisp said on Saturday.

"So this is horrific and traumatic, but we saw some incredible acts of bravery and people being prepared to help their fellow Melburnians and Victorians."