Heavy rain fell through the night, flooding many neighborhoods of Abidjan and leaving several key roads unusable.
The rain continued to fall on Tuesday morning.
"Flooding situation at 12:40 (GMT and local): 5 deaths. Operations are ongoing", the fire brigade said in a statement posted on social media.
It added that 77 people had to be rescued and one taken to hospital, while a building threatening to collapse was evacuated.
Over the past 24 hours, some neighborhoods in Abidjan have received around 200 millimeters (eight inches) of rainfall, the equivalent of several weeks of rain, according to data from the Ivorian meteorological agency.
Residents posted images on social media showing the extent of the flooding in their homes or neighborhoods and calling for help.
Last week, six people died after torrential rain triggered a landslip in the city's western neighborhood of Mossikro.
Landslides during the rainy season are a notorious risk in the fast-growing city of five million people, with flood-prone areas often inhabited by low-income citizens.
Previous accidents claimed 18 lives in June 2018 and 13 in June 2020.
