'Dad, I nearly died today': Teen pushes friend from path of 4WD in Flinders Street attack

A teenager has told how he almost died saving a friend from the path of the Suzuki that mowed down pedestrians at Flinders Street on Thursday.

Three victims remain in a critical condition after a white 4WD drove on tram tracks and deliberately hit pedestrians crossing the major CBD intersection about 4.40pm.

CCTV footage shows the car pull out of traffic and onto the tracks, accelerating into the crowd of Christmas shoppers before crashing into a bollard.

Ethan Caruso, from Brunswick East, told 7 News how he pushed his friend out of the vehicle's path to save his mate's life.

The 17-year-old said he and another man were clipped by the Suzuki as he shielded his friend from the vehicle.

"The man in front of me, who obviously got it worse off than I did, just ricochet off me.

"I was just like mid-air, the car just came across and whacked by right ankle," Ethan recalled.

His worried parents heard their son recounting the incident on the radio, and immediately called to see if he was alright.

"His first words he said to me were, 'Dad, I nearly died today'," his father Peter said.

"It was really shocking."

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The driver of the white 4WD was allegedly Saeed Noori, a 32-year-old Afghani-Australian.

An 83-year-old from Northcote and two South Koreans in their 60s, remain in a critical condition.

The youngest victim, a four-year-old boy - a South Korean national living in Hoppers Crossing - is in a stable condition.

The pedestrians who were admitted to hospital include nine foreign nationals from China, Italy, India, Venezuela, Ireland, South Korea, and New Zealand.

The driver was arrested after being dragged out of the car by an off-duty police sergeant, who had surgery for a hand injury on Friday.

He has been transported to Melbourne West Police Station this morning where will he will be formally interviewed by detectives.