Celebrations at the Calgary Stampede have been marred.

Three horses have died after a chuckwagon race Thursday evening.

Officials say one of the lead horses in the race collapsed for an unknown reason, then took three others down with him.

Three horses had to be euthanized on the track, while one other will survive, but requires surgery.

Animal welfare organizations and even celebrities such as former Price is Right host Bob Barker, have criticized the Calgary Stampede for failing to make the races safer. The Vancouver Humane Society is calling for the rest of the chuckwagon races to be suspended.

Stampede spokesman Doug Fraser calls it a ``tragedy'' and that the horses are cared for and loved by the chuckwagon drivers

In 2010, a total of 6 horses died during the Stampede.