Ecuadorian sprinter Alex Quiñónez was fatally shot in the port city of Guayaquil, police said early on Saturday.

Quiñónez, who was 32, became a national hero in 2012 when he reached the 200 metres final at the London Games, finishing seventh in a race won by Usain Bolt.

Guayaquil-based newspaper El Universo reported that Quiñónez was fatally shot on a street in the north-west section of the city around 9:20pm on Friday and that another man was also killed.

There were no immediate reports of arrests.

President Guillermo Lasso vowed in a statement on Saturday that the slaying "will not go unpunished".

Quiñónez's death was also confirmed by the Ecuadorian Olympic Committee in a statement on Saturday.

It said the circumstances of his death "have not yet been clarified".

Quiñónez won bronze in the 200 at the 2019 world championship in Doha.

Andrea Sotomayor, the secretary-general of the Ecuadorian Olympic Committee, expressed her sorrow and outrage on Twitter, decrying "so much evil".

"I don't have words to express the sadness, helplessness and indignation that is overwhelming me," wrote Sotomayor, who was formerly Minister of Sport.

Guayaquil and other parts of Ecuador have been struggling with high levels of crime.

This month, President Lasso decreed a state of emergency to confront drug trafficking and other crimes in Ecuador, saying the military and police will take to the streets to provide security.

This year, there have been revolts in the country's prisons due to drug violence, especially in Guayaquil, which have ended in massacres by inmates of rival gangs linked to Mexican drug cartels.

About 230 people have been killed in those compounds.