Olympics organizers postponed the men’s individual triathlon race that had been scheduled for Tuesday morning, saying water-quality tests had shown that the Seine, the river that traverses Paris, was unsafe to swim in.

The race will now be held on Wednesday morning, after the end of the women’s triathlon, the sport’s governing body, World Triathlon, said in a statement early Tuesday.

“The tests carried out in the Seine today revealed water quality levels that did not provide sufficient guarantees to allow the event to be held,” the organization said, adding that the race could be further rescheduled.

The Olympics’ official website said only that the men’s individual race had been rescheduled, citing “weather.”

This is a developing story.