Around midday local time, the workers heard cracking sounds and the building started to crumble around them, said caretaker and builder Jourdin Yoro.
"In a rush, we started to run," Yoro said. "Within about 45 seconds, the building collapsed."
Rescue efforts were ongoing at the site in Abidjan's upscale Riviera Palmeraie district on Saturday with emergency workers searching through a vast pile of shattered concrete and debris.
A further nine people were wounded in the collapse, said Charles Paolo, the head of the firefighting unit at the scene.
Such accidents are relatively frequent in Côte d'Ivoire and elsewhere in West Africa, particularly in the rainy season, due to poor enforcement of building regulations and the use of often substandard construction materials.
In 2022, the Côte d'Ivoire government said it would step up efforts to boost compliance with safe construction practices after thirteen people were killed in two building collapses in Abidjan within a two-week period in February and March.
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