Residents described how waters destroyed their homes, swept away household goods and damaged vehicles as Freetown, an overcrowded city of 1.2 million, was pounded overnight.
"The seven corpses were brought in intermittently overnight but we know that more will come," Amara Kamara, mortuary attendant at the city's main Connaught Hospital, told AFP.
Among the dead were three children, he said, giving their ages as three, four and 10.
Witnesses in the worst-hit areas described seeing people carried away by the floodwater as their homes were destroyed.
"I witnessed two primary school children being swept away when they stepped on a slab... so I am certain the death toll will eventually be higher," a resident of Brookfields in western Freetown told AFP.
It rains six months of the year in Freetown, one of the world's wettest cities, and putrid water from its populated slopes inundate its coastal slums every summer, causing cholera, dysentery and respiratory infections.
At least 20 neighbourhoods were flooded by the five-hour storm, according to a statement from the presidency that said the torrential monsoon rain would continue for at least six days.
Police and soldiers were deployed to the worst-hit areas to maintain law and order, while residents were being urged to stay at home, it said.
A doctor told AFP rainwater had inundated six wards at the Connaught, the country's largest hospital, forcing patients to be moved to makeshift treatment areas.
"We were able to contain the situation as we admitted over 100 people for abrasions, shock and hypothermia, while about 40 were treated and discharged," a separate medical source told AFP.
By 7:30am (0730 GMT), more than 600 people had sought refugee at the Brookfields National Stadium, worker Mohamed Sillah said.
The 45,000-seat stadium, home to the national football team, is one of two Freetown sports grounds where emergency services were telling people to take refuge.
Sillah said emergency workers were distributing drinks, bread and foam mattresses.
"The raging waters took away all my property," housewife Fatu Kargbo told an AFP correspondent on the Fourah Bay College slope in the east of the city.
"I have three children and four grandchildren who suffered some bruises and cuts but neighbours were able to rescue them before they were dragged away."
Mamie Sillah told AFP she had lost everything as the waters hit the Kroo Bay slum in central Freetown.
"I wonder whether it is worth living now. What I am wearing now is all I have," the 45-year-old said.
Five Red Cross emergency operations were at work plucking frightened residents from flooded neighbourhoods while at least three major bridges linking the city centre to its rural western edge were reported damaged.
"We were able to rescue at least 20 people, including children from school, who would have lost their lives," Teddy Jones, a leader of one of the teams, told AFP.
The government was to hold an emergency meeting headed by Vice-President Victor Foh, who is coordinating the relief efforts.
"The situation is serious and hundreds of people have been affected," Mary Mye-Kamara, the government's director of disaster management, told reporters.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ