MELBOURNE - He had only a bat, but he ran out onto the road to try to stop a crazed driver who later killed three people in the Melbourne city centre.

Photos and videos of the unnamed man confronting a car that was doing wheelies, or circles, in the middle of an intersection outside Flinders Street Station have emerged online.

A video by a witness shows two men running out to the car. One of the men swings a bat at the vehicle, and both are nearly hit by the maroon car.

They quickly run back to the pavement after that.

Many netizens praised his actions as brave, but some questioned how wise it was to try to stop the fast-moving car with a bat.

The driver later drove up Bourke Street Mall, a busy pedestrian street, and aimed the car at pedestrians.

Twenty were injured and three died, reports said.

Police chased and fired at the errant driver and a police car reportedly rammed into his car.

When the car finally came to a stop, the driver was dragged out by police officers.

Heavily armed officers were deployed around the scene as television footage showed the badly damaged car with the front doors open and the windscreen smashed.

A handcuffed man in his underwear was seen lying on a footpath surrounded by police.

Police had shot the 26-year-old male driver in the arm.

Police said they were not considering the incident an act of terrorism.

Victoria police commissioner Graham Ashton said the offender was a man long known to them for violent behaviour towards his family, drug and mental problems.

He was also in a stabbing incident overnight involving his brother.