( CNN ) -- Night had fallen . Some 20 airplane passengers had taken their seats for the short hop from Brussels , Belgium , to Zurich , Switzerland . Unknown to them , a precious cargo was being loaded into the airplane hold along with their suitcases : $ 50 million in rough and polished diamonds . But the diamonds would never reach their final destination . Shortly before 8 p.m. Monday , eight masked men in two vehicles burst through the perimeter fence of Brussels Airport and sped toward the aircraft on the tarmac . The men , who authorities said wore clothing resembling police uniforms , were heavily armed . While no shots were fired and no one was injured , the pilot , co-pilot and a transport security guard were all threatened at gunpoint , said Ine Van Wymersch , of the Public Prosecutor 's Office in Brussels . Within three minutes , the thieves had snatched the diamonds from the hold , said airport spokesman Jan Van der Cruysse . Drag queens , fake beards and chocolates : Notable diamond heists . Moments later they left the scene , racing out through the same breach in the airport periphery through which they had entered . The robbers , four in each car , had broken a hole in the fence where it ran between two construction sites , Van Wymersch said at a news conference . `` This was a very precise , almost military-organized and well-executed robbery , '' Van der Cruysse said . He said it was a `` big surprise '' that such a slick heist been possible -- but pointed the finger at organized crime . `` We are an airport that is , as all international airports are , subject to very strict aviation security and safety regulations , '' he said . The aircraft targeted was a regular passenger flight operated by Helvetic Airways on behalf of Swiss , Switzerland 's national airline . It 's not yet clear how the thieves knew that the diamonds would be on board . But this was not a chance holdup , said Van Wymersch , describing the men involved as `` professionals . '' Antwerp , the city known as the world 's diamond-cutting capital , lies only about 25 miles away from Brussels . The Antwerp World Diamond Centre has on average $ 200 million in stones coming in and out daily , and it takes security very seriously , a spokesman told CNN . He was unable to confirm reports that gold and platinum were stolen along with the diamonds . It 's not the first time that Antwerp 's centuries-old diamond trade has been targeted . The city was the scene of a spectacular robbery in 2003 when thieves made off with the contents of more than 100 safes at the diamond center . Those gems were never recovered . Some 34,000 jobs in the city are connected to the diamond trade , according to the Antwerp World Diamond Centre , from mining company representatives to dealers to the craftsmen who polish the stones . Netherlands art heist suspects arrested . 3 arrested in massive maple syrup heist .
Thieves were dressed like police and threatened air crew at gunpoint , prosecutor says . Team of eight takes three minutes to steal the rough and polished stones from a plane 's cargo hold . They breached the periphery and sped off with their haul in eight vehicles , the spokesman says . The stones were en route from Switzerland to Switzerland , Antwerp , Antwerp diamond center says .