Dramatic footage has emerged of the moment police arrested a violent teenager accused of mowing down pedestrians during a rampage on AFL Grand Final day in Melbourne.

The CCTV, obtained by the Herald Sun , can be shown after the 15-year-old pleaded guilty to a string of charges at Melbourne Children’s Court yesterday.

The boy, who cannot be named because of his age, can be seen exiting a stolen car outside Flinders Street station dressed in full combat gear, including a backpack, and armed with a knife and a baton.

The boy drove at pedestrians and cyclists, doing skids and running red lights in the Melbourne CBD on AFL Grand Final day. (Herald Sun) (Herald Sun)

The car narrowly missed pedestrians who fled for their lives. (Herald Sun) (Herald Sun)

As he refuses police demands to drop the weapon and lie on the ground, one officer sprays the boy with pepper spray before the teen lunges at him.

The policeman falls backwards onto the tram tracks before two more officers run in.

The boy is hit with a stun gun before he is taken into custody.

The arrest ended a terrifying rampage, during which he nearly pinned a pair of pedestrians against the Federation Square information centre with the car before they jumped out of the way at the last moment.

A man attempting to stop the driver threw his hire bicycle behind the vehicle. (Herald Sun) (Herald Sun)

The actions of the officers were praised in court, with Prosecutor Mark Gibson SC saying they “executed appropriate restraint and tremendous bravery”.

"(They) did not know what was in the backpack - whether it contained an improvised explosive device or incendiary weapon," he said.

“But for their approach, the end result may have been a lot different."

The teen was originally charged with 14 offences, including two of attempted murder, but several were struck out yesterday following negotiations.

One police officer then sprays the teen with capsicum spray before he lunges at him, knocking the officer to the ground. (Herald Sun) (Herald Sun)

After more officers run in, the teen is tackled to the ground and hit with a stun gun. (Herald Sun) (Herald Sun)

A map of Melbourne's CBD was found on his bedroom wall along with army-related items and artefacts. But it was not suggested he was trying to carry out a terror-related act.

The boy was diagnosed with autism after his arrest, with his lawyer saying the youngster struggled with the "complex" world of high school and adolescence, and had insufficient support for his disabilities".

"His sense of shame for being different seems to have increased, illustrated by his attempts to hide his hearing aids," the boy's lawyer said.

"He was suffering from isolation and frustration as a result of his needs not being met over a long time."

But he posed little risk to the community since supports had been put in place, the judge heard.

He spent three tough months in custody before being bailed in January and is unlikely to receive a sentence of detention - with prosecutors not seeking one.

The judge said a probation order was likely but the seriousness of the crimes had to be considered.

The boy will be sentenced on March 14.