A teenager at Don Dale is seen through the fence. (ABC)

A teenager at Don Dale is seen through the fence. (ABC) Source: ABC

The youth justice advocate says he fears for the teenagers who are currently being held behind bars in Darwin.

Dylan Voller, who became the face of the juvenile detention scandal two years ago, wants the Northern Territory to close the Don Dale youth detention centre.

The notorious facility has been declared a crime scene and not operational after a group of teenagers set fire to the centre’s school and appeared to try to escape on Tuesday night.

Worried relatives watched on as firefighters extinguished the flames and armed police arrived to recapture the teenagers.

All 25 youth detainees are currently being held at Darwin police station.

“They’re not bad kids,” Mr Voller told NITV News.

“They’ve made terrible mistakes and they need help. They’re not getting help in that place.”

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The NT government has agreed to close the centre but a replacement is still at least several years away.

Authorities have blamed the recent spate of violent incidents at the centre on the fact that it's a former adult prison not 'fit for purpose' for rehabilitating young offenders.

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“I do respect their wish to protest,” Mr Voller said.

“I just want to send a message to them that there are better ways to go about it.”

Images of Mr Voller wearing shackles and a spit hood caused national outrage when they were aired on TV in 2016.

It prompted the Australian government to appoint the royal commission into youth detention in the Northern Territory.

Asked what has changed since then, Mr Voller replied "obviously nothing if this sort of thing is happening."

“That place is a threat to all these young kids,” he said.

“There’s a lot of people that love them. There’s a lot of people that support them and Australia knows there’s still a lot of stuff happening in there.”