Approximately 21 people were killed, and nearly 2,000 inmates escaped during the attack on a military depot and the country's central Pademba Road Prisons, according to media reports citing Sierra Leone's Army spokesman, Colonel Issa Bangura.
The casualties included 13 soldiers, three assailants, a police officer, a civilian, and a private security worker, as reported by Bangura. He added that eight people were wounded, and three were arrested.
The prison officials revealed in a report that a total of 1,890 inmates escaped, while 23 have returned, the media said.
The acting director general of the Sierra Leone Correctional Service, Colonel Shek Sulaiman Massaquoi reportedly noted that the attackers used a vehicle to ram open the main gate after shooting, and a rocket launcher did not help to penetrate the prison's defenses.
The escaped prisoners were urged to return to the prison by the police, which also promised a reward for information about the fugitives or the assailants, the outlet said.
On Monday, Sierra Leone's President Bio met with Nigerian and the Economic Community of West African States (ECOWAS) delegations, who expressed "their readiness to work with [Sierra Leone] towards forestalling any future security occurrences," the leader said on social networks.
"We are deeply thankful for the tremendous outpouring of support from key allies around the region and world," the president said.
ECOWAS, along with the European Union, denounced the Sunday attack in the West African country, calling it an attempt to violate the constitutional order.
The November 26 attack on Sierra Leone's weapons depot in Freetown and the prison prompted the government to impose a curfew across the country, which was then limited to the nighttime hours of 9:00 pm to 6:00 am local time every day "until further notice." The head of state later announced that "most of the leaders" who overrun a military arsenal were detained and "investigations are ongoing."