Diamond heist: Robbers steal £32m worth of precious stones at Brussels Airport Eight men cut hole in security fence and burst through in fake police cars Gang were armed with machine guns, but seized gems without firing a shot Robbers sped off through same gap in fence just a few minutes later Thought stones belonged to diamond and gold traders in Antwerp Eight masked gunmen made a hole in a security fence at Brussels' international airport, drove onto the tarmac and snatched some $50million (£32m) worth of diamonds from the hold of a Swiss-bound plane without firing a shot. The gang used fake police cars in their daring raid late yesterday, grabbed the cache of stones and sped off into the darkness. 'They tried to pass themselves off as police officers,' said Anja Bijnens, spokeswoman for the Brussels prosecutor's office. Smash and grab: Armed robbers have stolen diamonds worth more than £32million as they were being loaded on to this plane at Brussels airport Brazen: An airport spokesman said the robbers made a hole in the perimeter fence and drove up to the Swiss passenger plane, which was ready to leave, while wearing outfits that resembled police uniforms They reportedly wore outfits which resembled dark police clothing and both cars had blue lights on top, she said. Police found one burnt-out vehicle close to the airport later that night and said they were still looking for clues. The heist was estimated at some $50million (£32m) in diamonds, said Caroline De Wolf of the Antwerp World Diamond Centre. 'What we are talking about is obviously a gigantic sum,' De Wolf said. Late arrival: Security staff place barriers along the safety fence, where the armed robbers are believed to have burst through before making a beeline for the diamonds as they were being loaded onto the plane Brazen: The gang threatened staff and seized two locked metal trunks containing the valuables as they were being loaded onto a Helvetic Airlines flight to Zurich at around 8pm on Monday night An airport spokesman said the robbers made a hole in the perimeter fence and drove up to the Swiss passenger plane, which was ready to leave, at about 8pm. The bandits then got out and pointed the infra-red sights of their assault rifles on terrified Brink's security guards who were guarding an armoured van before taking the loot in two locked metal trunks from the hold. Without firing a shot, they drove off through the same hole in the fence, completing the spectacular theft within barely five minutes, Bijnens said. Airport spokesman Jan Van Der Cruijsse could not explain how the area could be so vulnerable to theft. 'We abide by the most stringent rules,' he said. The Swiss flight, bound for Zurich and operated by Helvetic Airways, was canceled. Swiss, an affiliate of Germany's Deutsche Lufthansa AG, declined to comment on the heist, citing the ongoing judicial investigation. Great escape: The gang used two black cars in their raid, grabbed the cache of stones and sped off into the darkness, said Anja Bijnens, spokeswoman for the Brussels prosecutor's office On alert: A truck from the security company Brink's is seen at the airport's cargo zone after the heist A decade ago, the Belgian city of Antwerp, the world capital of diamond-cutting, was the scene of what was probably one of the biggest diamond heists in history. Robbers took precious stones, jewels, gold and securities from the high-security vaults at Antwerp's Diamond Center, yielding loot that police in 2003 estimated to be worth about $100 million. Antwerp's Diamond Center stands in the heart of the high-surveillance diamond district where police and dozens of cameras work around the clock. Security has been beefed up further since the spectacular 2003 robbery. But it is thought the goods stolen in Monday's raid, 30 miles away in Brussels, may have belonged to those very traders who that security is trying to protect. The insurance for air transport - handled sometimes by airlines themselves or external insurance companies - is usually relatively cheap because it's considered to be the safest way of transporting small high value items, logistics experts say. Unlike a car or a truck, an airplane cannot be waylaid by robbers once it's on its way, and it is considered to be very safe before the departure and after the plane's arrival because the aircraft is always within the confines of an airport - which are normally highly secured. Philip Baum, an aviation security consultant in Britain, said the robbery was worrying - not because the fence was breached, but because the response did not appear to have been immediate. That, he said, raised questions as to whether alarms were ringing in the right places. 'It does seem very worrying that someone can actually have the time to drive two vehicles onto the airport, effect the robbery, and drive out without being intercepted,' Baum said. That amount of time would also allow someone to board the plane, he said. Police said an Audi saloon made to look like a police car with a flashing blue light was used in the raid, together with a Mercedes van. The burnt-out Mercedes was found in a suburb of Brussels within an hour of the raid on the Helvetic Airways plane. Precious: The robbers made off with a cluster of diamonds like this worth an estimated £32.3million ($50m) Investigation: Prosecutor's office employees Anja Bijnens and Ine Van Wijmersch update the media A Brussels Airport police spokesman said a full investigation has been launched into the raid which happened shortly before 8pm as transport agents loaded the plane with cargo destined for one of the Swiss city's many secure banking vaults. He said: 'Two vehicles got through security by breaking through a damaged barrier. No shots were fired during the attack, which was over within three minutes. VIDEO Robbery gang make off with $50m of diamonds