Alleged Bourke St driver "ranted" at Today journalist live on air, hours before killing.

The alleged Melbourne rampage driver, who killed four people when he ploughed into pedestrians in Bourke St, “ranted” at a Today Show journalist live on air hours before the incident.

Neary Ty was standing on a footpath in Windsor when the driver pulled up behind her in a maroon Holden Commodore. He wound down his window and began ranting and waving his red hat at the camera.

The journalist was reporting on the stabbing of a young man in Windsor, which the police now confirm involved the driver of the Commodore.

The driver, 26-year-old Dimitrious Gargasoulas, would go on to kill four people and injure approximately 15 more, after deliberately targeting pedestrians in Melbourne’s CBD shortly before 2pm yesterday.

“We were doing a live cross this morning for the Today Show around 8am this morning about this stabbing in Windsor when the Holden Commodore pulled up behind me,” Ty told Nine News.

“The man started ranting and raving and swearing. He was waving his red hat out of the window. At this point I was live on air. I couldn’t see what was going on.

Ty said the driver then returned the scene ten minutes later as the crew was packing up.

“He was parked on the side of the road. We thought it was a bit strange he was there. We had no idea who he was.

“I walked past him and I noticed that he was wearing a gold chunky bracelet which was similar to a gold chunky necklace that was found at the scene during this fight.

“He was there for a while. He didn’t seem erratic while he was sitting in the seat. He remarkably was there around 10 minutes after police and SES had left the scene. We packed up and left," she told Nine.

When news broke of the rampage in Bourke St, Ty's cameraman called her to say: “I think it’s the same car that’s involved.”

“We look at the horrifying amateur vision of that driver driving erratically and noticed there was a bit of green tape underneath the registration plate. That’s when we realised it was the same man.”

Ty said it was “certainly very shocking, very sad to hear this man’s been involved in this awful tragedy in Bourke St”.