(CNN) -- Eight masked thieves stole $50 million in rough and polished diamonds in a lightning-fast heist Monday at Brussels Airport, the Antwerp World Diamond Centre said Tuesday.

The stones were en route from Antwerp, Belgium, to Zurich, Switzerland, a spokesman for the diamond center said, citing police.

Police told the diamond center that the robbers, who used two vehicles, breached a security gate when the goods were already on an aircraft.

Jan Van der Cruysse, a spokesman for Brussels Airport, told CNN that it took the thieves only three minutes to rob the cargo hold and that they left the scene minutes later.

He said the robbers, who arrived in two cars, breached the airport periphery and sped to the airplane. They then removed items from the hold before leaping back into their vehicles to escape through the same breach.

They were heavily armed, but no shots were fired, he said.

At the time, there were about 20 passengers on board the aircraft, which was a regular passenger flight from Brussels to Zurich operated by Helvetic Airways on behalf of Swiss, Van der Cruysse said.

"This was a very precise, almost military-organized and well-executed robbery," he said.

"We are an airport that is, as all international airports are, subject to very strict aviation security and safety regulations," he said.

The airport, which is governed by Belgian and European regulations, generally has an excellent reputation, he said.

"It comes as a big surprise that something like this is possible. But of course, this is rather connected to banditism and organized crime rather than aviation security," he said.

The spokesman for the Antwerp World Diamond Centre said it was aware of reports that gold and platinum were stolen along with the diamonds, but he said he could not confirm that information.

On average, the Antwerp World Diamond Centre has $200 million in stones coming in and out daily, and it takes security very seriously, he added.
$50 Million In Diamonds Stolen At Brussels Airport