The protests were over alleged economic hardships and bad governance by President Julius Maada Bio’s government.
The protesters, mainly youths had gained entry into the country’s Lungi airport after the military and police unsuccessfully tried to stop them.
Some of the protesters were demanding that President Bio must go.
Residents accused the police on Wednesday of firing live bullets at the protesters resulting in violent clashes and the deaths.
In a statement ECOWAS said it “strongly condemns the violence that occurred in many locations in Sierra Leone and have led to loss of lives.”
ECOWAS called “on all to obey law and order and for the perpetrators of the violence to be identified and brought to justice, in accordance with the law.”
President Bio said in his national address that “This was not a protest against the high cost of living occasioned by the ongoing global economic crisis.