Gang members dressed in military uniforms barricaded a garbage truck near the town of Sassari and stopped a convoy of armored vehicles on their way to distribute money to regional post offices.
In the robbery, which took place at around 8 a.m., they first opened fire on the convoy, hitting one of the security guards in the leg, and then used grinders to cut through the armored vehicles and take the money.
The attackers armed with Kalashnikovs fled the area after seizing 4 million euros in pensions.
The team's tactics have been likened to those of a gang operating in the southern Italian town of Cerignola, which has carried out a number of similar high-profile robberies, as well as those of the Fast & Furious movie series.
THE GANG THAT MAKES DEALS WITHOUT TALKING
Police launched an investigation and manhunt and found a bag filled with explosives on the side of the road. Two getaway cars were also found abandoned.
One of the drivers told the local newspaper La Nuova Sardegna that the team was very well organized: "They understood each other without speaking."
Highway robberies are becoming increasingly common in Sardinia. There have been more than ten similar incidents in the last decade.
Lorenzo Tramaglino, president of the confederation representing private security guards, emphasized that their work is becoming increasingly dangerous. He said the country's 60,000 private security guards were neither adequately protected nor paid enough to take the risk.