Ecuadorian sprinter Álex Quiñónez was fatally shot in the port city of Guayaquil, police said on Saturday.
The sprinter was shot along with another person outside a shopping centre. The motive is yet unclear.
Ecuador’s athletics federation described the 32-year-old as the country’s greatest sprinter.
President Guillermo Lasso promised that those behind the killing will be found and punished.
It comes after a 60-day nationwide state of emergency came into force in Ecuador on Monday in response to a wave of violent crime.
Official figures suggest the number of murders in the first eight months of this year are double those in the same period last year.
“With great sadness, we confirm the murder of our sportsman Alex Quiñónez,” the Sports Ministry announced on Twitter.
“We have lost a great sportsman, someone who allowed us to dream, who moved us….he was the greatest sprinter this country produced.”
Mr Quiñónez won bronze in the 200 metres at the 2019 World Athletics Championships in Doha. He was suspended prior to the Tokyo Olympics due to “breach of his whereabouts obligations”.
President Lasso tweeted his condolences.
“May he rest in peace. Those who take the lives of Ecuadoreans will not remain unpunished,” he said.