DAKAR, Senegal -- The Senegalese military says 13 people have been killed by armed gunmen in the country's southern Casamance region. The bloodshed confirmed late Saturday by Col. Abdoul Ndiaye was the worst in years and immediately sparked fears of renewed unrest in the south, where separatists have sought independence for more than 30 years in the West African nation.

Despite the presence of separatists, Casamance had been relatively calm since 2012.

Ndiaye said the victims had been searching for firewood just outside the town of Ziguinchor. Their deaths came hours after the release of two prisoners belonging to the separatist group known as the Movement of Democratic Forces of Casamance (MFDC).

Get Breaking News Delivered to Your Inbox

While there was no immediate claim of responsibility for the slayings, suspicion fell on the separatist group.

BBC News reports that Casamance has seen a long-running conflict between the government and the MFDC rebel group, which wants independence. The Senegalese military said the attack may be connected to the release of two members of the group from custody.