Shoppers and staff recall moment they ran for their lives as shopping centre brawl unfolded

Shoppers and staff have recalled the moment they felt they were running for their lives as a wild brawl erupted between gangs with machetes inside a Melbourne shopping centre.

Four youths have been arrested over the violent attack, with two already out on bail.

Security footage from the busy Northlands shopping centre on Sunday afternoon shows one teen allegedly slashing another with a machete in the food court.

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A little girl eating her ice cream just metres from the violence can be seen being scooped up into the safety of her mother's arms.

But the fighting continued, with one thug pinned down as a Good Samaritan removed the large blade.

An injured man collapsed beside the ice cream shop as terrified shoppers ran.

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The brawl unfolded about 2.30pm.

Police said two rival gangs had organised to meet up before the fight broke out.

As shoppers and workers were forced into store rooms, one man, Anthony, used a chair to defend himself while another performed a citizens' arrest.

"He had a balaclava on and a machete swinging it around so I thought ... I wasn't going to stand for that," Anthony said.

"I just kinda jumped down onto his back and and just took his back and someone else took the machete from him."

Police have praised the actions of bystanders and staff who helped keep the community safe, offering water and comfort inside the stores.

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Police are looking to give Anthony a bravery award for his efforts.

The two main alleged instigators, boys aged 16 and 15, were already on bail for serious weapons offences.

They have been charged and remanded.

Two other men aged 20 and 18 were arrested and have already been bailed.

A 20-year-old man is in hospital with serious head injuries.

Three others are on the run.

"We've already identified all of those who were involved, with more arrests imminent, so I urge anyone who was involved to hand themselves in," Deputy Commissioner David Clayton said.

For some, fear has turned to anger.

Just six months ago at the same shopping centre, Mykey O'Halloran's partner was slashed with a machete and robbed by a gang of teenagers.

"I don't want to live in fear and I want to be able to come to the shops and not have teenagers rule my life," O'Halloran said.

There are concerns the centre, run by Vicinity Group, hasn't done enough to protect customers and staff

It took more than 30 minutes for the shopping centre's alarm to be triggered.

Vicinity Group says it will remain focused on reviewing and strengthening safety procedures.

Cafe owner Bryan Jim says this incident shouldn't reflect on the centre's staff.

"Northland is still safe," Jim said.

The police presence will be bolstered all week and into the weekend.