(CNN) -- Authorities will have to await a necropsy to find out killed one of the equine world's top athletes, a stallion named Hickstead.
Hickstead collapsed and died in front of hundreds of spectators at the Rolex F.E.I. World Cup in Verona, Italy, on Sunday.
The Dutch Warmblood stallion completed the 13-track show jumping course and collapsed on the ground under his rider, the reigning Olympic champion and world number one Eric Lamaze.
As shocked fans watched, Hickstead lay shaking on the ground for several minutes before he died. A dazed Eric Lamaze was then led out of the ring.
Officials stopped the competition at the request of the riders.
"Hickstead really was a horse in a million and my heart goes out to Eric and everyone connected with this wonderful horse," said Princess Haya bint Al Hussein, the wife of the prime minister of the United Arab Emirates and the president of the sport's governing body, Federation Equestre Internationale.
"This is a terrible loss, but Hickstead truly will never be forgotten. We were very lucky to have known him."
Lamaze rode Hickstead to win an individual gold for Canada at the 2008 Summer Olympics in Beijing, and countless Grands prix and Nations Cup victories.
"Our deepest sympathies go out to the owners, to Eric and to all the connections of one of the greatest jumping horses of all time," said FEI Jumping Director John Roche. "Hickstead's presence on the circuit will be very sadly missed."
A necropsy to determine the cause of death is scheduled in the coming days.