A 15-year-old boy has been charged with two counts of attempted murder and six counts of recklessly endangering life, after allegedly trying to run down people in Melbourne’s CBD on AFL grand final day.

The boy, from Melbourne’s eastern suburbs, is also facing charges of assaulting police and resisting a police officer and was remanded in custody.

He will appear in a children’s court at a later date.

He was tasered and arrested by police about 8am after a car was driven erratically in reverse down Swanston Street towards the intersection of Flinders St Station and Federation Square.

It is alleged the boy, who was dressed in black military-style clothes and a helmet which covered his face, was carrying some kind of weapon.

Eyewitness Jolon Cooke was helping set up grand final equipment in Federation Square at the time.

The car allegedly driven by the teen surrounded by police. Photo: ABC

He said he thought he would be killed, alleging the car was being driven at him.

“He came out of the car with a black baton, full head-to-toe black military gear, took a backpack out of the car,” Mr Cooke said.

Bystanders were heard on video yelling, “Shoot him, shoot him.”

Police Acting Superintendent Wayne Newman said on Saturday the boy was believed to have had a history of mental illness and said the incident was not linked to terrorism.

However witness Jason Smith said the person “looked like a terrorist” and said someone had thrown a pushbike at the car to try to get it to stop.

“Then the cops eventually got up close and went out of view a bit so they tasered him then that was it,” he said

“We were hiding behind the wall for safety in case there was an explosion and it was really, my heart rate … as soon as I saw him all in black, [it was] just scary as,” Mr Smith said.

Officers at the scene where the teenager was arrested. Photo: ABC