The country's Vice President, Victor Foh, yesterday said it was likely that hundreds were lying dead underneath the rubble.
Mr Koroma urged residents of Regent and other flooded areas around Freetown to evacuate immediately so that rescue workers could continue to search for survivors who might be buried underneath debris.
Authorities say more than 300 people were killed in and around Freetown on Monday following heavy rains.
IsraAID, which now offers long-term aid programs in 17 countries, helped train many local professionals in psychological assistance, stress relief, and self-care.
Dramatic pictures show streets that have turned into churning rivers of mud.
Emergency services have been put in place as vehicular traffic has been severely hit.
Aid agencies said there were immediate concerns for thousands of people in the capital, who may not have access to water that is safe to drink.
"It's very hard to paint what the reality looks like, because it's more scary and very sad and disastrous than anyone can be able to describe", he said.
"The bodies were collected in areas that experienced flooding and mudslide this morning in the city of Freetown", Kamara said. In 2015, ten people were killed and thousands became homeless in floods caused by the monsoon rains.
"These emergency funds will enable volunteers to assist more than 9,000 people with search and rescue, first aid, health care, water, sanitation and hygiene promotion and emergency food", IFRC said.
Linnea Van Wagenen of the United Nations told The Guardian that they were using satellite imagery to map out the scale of the disaster, and warned that there could be more mudslides.
James Chfwelu, National Director of Christian charity World Vision in Sierra Leone told Premier that while they were prepared for heavy rain, "the devastation this year has been worse".
Some impoverished areas in Sierra Leone's capital are near sea level and have poor drainage systems, which increases flooding during rainy season.
We must stand with Sierra Leone as they are faced with their next challenge.
The number of survivors still remains unknown but sources at the Connaught said about 20 survivors with severe injuries are now responding to treatment.