All five people involved in the Brisbane Street Mall assault have been identified.

Three were interviewed on Sunday afternoon.

Two more are expected to be interviewed within the next 24 hours.

Tasmania Police Detective Inspector Kim Steven said all five are likely to be charged with assault and stealing.

EARLIER:

A 16-year-old male is in police custody after he allegedly helped carry out a "savage attack" in the Brisbane Street Mall.

Early on Sunday morning, a 25-year-old man was knocked unconscious after being approached by five people.

Tasmania Police is urging four other females, allegedly involved in the attack, to come forward. It is understood at least three of those involved are under the age of 18.

Tasmania Police Detective Inspector Kim Steven said the alleged offenders had been identified.

"They're young females and we would urge them to come forward to speak to us. We will be tracking them down either later [Sunday] or [Monday] morning," he said.

"We know who you are. It's not the end of the world. We need to speak to you. We will be speaking to you. It's better you coming with a parent or guardian and we'll deal with it from there."

IN OTHER NEWS:

The man was left unconscious for a short amount of time and his mobile phone and wallet were stolen.

A passerby took the man to the police station, and Ambulance Tasmania attended. However, he was not taken to hospital.

Inspector Steven said it was understood there was a confrontation that unfortunately got out of hand.

Police are working through how the people and the group were known to each other.

"I don't think people realise how quickly these things can escalate. A person only has to fall and hit their head and we can be dealing with a death very, very quickly," he said.

"From what I've seen in the footage, that certainly wasn't the intention in this occasion ... I just urge people to take a step back and walk away from these things and, hopefully live to be around another day."

Police said the alleged offenders were identified through some "very good CCTV".

The incident happened about 1.45am.

Police would like to reassure the public that this appears to be an isolated incident.

All alleged offenders are believed to be about 170-175 centimetres tall and of Caucasian appearance.

If anyone witnessed the incident or has information that may assist, Tasmania Police urge them to phone 131 444. Information can also be provided through Crime Stoppers on 1800 333 000.

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