The youths, aged between 14 and 24, have been charged by the North West Regional Crime Squad with more than 400 serious offences ranging from armed robbery to commercial burglary, car theft, driving offences and illegal gun possession.

The six-month investigation by the squad, which was established to target mid-level organised crime, revealed two syndicates based in Melbourne's northern suburbs have targeted department stores and tobacconists from Broadmeadows to Frankston.

Police have warned the criminal activity has become increasingly sophisticated and often uses social media and encryption apps to co-ordinate gang members.

"When all the 14-year-olds are 19 and the 21-year-olds are 26, we're going to have a big cohort of young men who are serious offenders who have a long history of high-risk, high-level offending, which is going to be problematic," Assistant Commissioner Stephen Leane said.

The squad's officer-in-charge, Detective Senior Sergeant Jeff Cocks, said within six months, the groups allegedly stole $3.3 million in iPhones, iPads and cigarettes, which were used to pay for designer clothes, drugs, sex workers and luxury hotel rooms.

"It's a fast and furious lifestyle where they spend as quick as they get it," Senior Sergeant Cocks said.

"It's a lifestyle where they party up, and party up could be anything from drugs, girls, to the casino."

Gang members and associates have boasted about their exploits on their Facebook sites, which include "selfies" with fast cars and designer "man bags" along with photos of guns, international crime figures and fictional gangsters.

Mr Leane said Facebook, as well as secretive messaging apps, were also used to recruit members and plan the next hit.

"They've all got Facebook accounts and those sorts of things so they're networked in the modern way. They're not just a group of five or six that know each other and hang around," he said.

A culture of bragging and striking a pose holds a strong draw for many.

The alleged ringleaders are believed to include 18-year-old David Margus, of Glenroy. Mr Margus is awaiting sentencing after pleading guilty in the Broadmeadows Magistrates Court earlier this month to commercial burglaries, theft, possessing proceeds of crime and going equipped to steal.

Police said the connection gang members have to fully-fledged criminals meant they were schooled in counter-surveillance. One of the main tactics was keeping the syndicates fluid by using different groups of teenagers for each burglary, which are usually committed in stolen cars to avoid detection.

"Just because they're young, don't think they're not structured and organised," Senior Sergeant Cocks said.

Police said the gang members conducted themselves with impunity, often taunting police by driving at 200km/h on major roads because they know the revised police policy no longer allows officers to engage in high-speed pursuits.

Police were also increasingly concerned about their own safety following a spate of attacks.

Broadmeadows man Mahmoud Taha, 19, was sentenced to an 18-month community corrections order last month after pleading guilty to assaulting police. Taha smashed the windows of an unmarked police car while the officer was inside.

Another two alleged syndicate members were arrested last week over threats to inflict serious injury on police. Last Wednesday, a female investigator was verbally abused after giving evidence against an associate during a bail application in the Broadmeadows Magistrates Court.

Detective Senior Constable Meagan Cornish was called a "f***ing dog" in an explosive outburst by the brother of a man police alleged in court was a syndicate associate, Marten Meschu. Mr Meschu's application for bail was refused.

Mr Meschu, 24, was charged by the squad two weeks ago with serious driving offences over a 2009 car crash in Broadmeadows that allegedly caused a heavily pregnant woman in another car to lose her 37-week-old unborn child. Police allegedly linked Mr Meschu to DNA found on the offending car during their recent investigation.

Assistant Commissioner Leane confirmed the force had taken the unusual step of employing a researcher in a bid to understand what underpins the high-risk behaviour and how to better engage with disenfranchised young men.

"They won't talk to cops, but we need to talk to other people downstream who may be able to have those conversations," Mr Leane said.

"The risk for us and the risk for the community going forward is if they've developed this very quickly as a lifestyle, what does that mean in the next five or 10 years? We need to break the cycle now."

Some of the youths police allege are members of the north-west crime syndicate

Glenroy man David Margus, 18, is allegedly one of the ringleaders of the syndicates. Margus pleaded guilty in the Broadmeadows Magistrates Court on August 4 to burglary and theft on a number of commercial premises, possessing proceeds of crime and going equipped to steal. He is awaiting sentencing.

Broadmeadows man Mahmoud Taha, 19, was sentenced in the Broadmeadows Magistrates Court on July 10 to an 18-month community corrections order and 150 hours of community service. He pleaded guilty to assaulting police and criminally damaging a police vehicle.

Roxburgh Park man Rickard Markhail, 19, pleaded guilty in the Broadmeadows Magistrates Court on August 4 to burglary and theft on a number of commercial premises, possessing the proceeds of crime and going equipped to steal. He is awaiting sentencing.