Saint Lucia celebrated Sunday after sprinter Julien Alfred stormed to victory in the women's 100m in Paris for the tiny Caribbean nation's historic first Olympic medal.

Alfred upstaged the much-hyped American world champion Sha'Carri Richardson on Saturday, clinching a stunning win in 10.72sec.

In the Saint Lucian capital Castries, the 23-year-old became an instant hero.

Cuthbert Modeste, who was Alfred's first coach, said he had trained her since she was nine and was impressed to see her "moving so easily" on the track.

He told AFP that when he saw her in her heat, on the way to the final, he had said: "Yes, the gold is ours."

Milton Branford Jr, a media production business owner, said the golden moment was simply "awesome".

"This is a singular moment in history for Saint Lucia that we will remember for the rest of our lives. I'm so, so proud about everything she has accomplished so far."

Another local, Samantha Agard, said that the landmark gold medal was a "big thing, not only for the country but also for the youth", praising "somebody who started from scratch and made it big".

She said the sprinter -- known by her nickname "Juju" -- will inspire younger people to take up sports.

Getting to the top of the podium was not a smooth passage for the devout Christian, whose victory came in front of 69,000 spectators in Paris, just 110,000 less than the population of Saint Lucia.

At the age of 12 her world was rocked when her father died, and she briefly stepped back from athletics altogether. She has credited coach Modeste with convincing her to return to the sport.

Two years later she decided to go to school in Jamaica, the home of her idol Usain Bolt, where she developed into a superb sprinter.

The athlete pinpoints winning the 100m silver medal in 2018 at the Youth Olympic Games as a turning point in her career -- also marking another first for the Caribbean island.

But her home nation of Saint Lucia has retained a special place in her heart, with the sprinter updating her profile picture on Facebook to show a photo of her post-run with the words: "For St. Luc1a".

"She has done us proud and we are absolutely, absolutely, very, very ecstatic about this," said Branford.