DAKAR, Senegal — Gunmen in Senegal on Saturday killed at least 13 people who were gathering firewood in the forest, the military said. It was the worst attack in years in the restive Casamance region in the country’s south, where a separatist insurgency has dragged on for more than three decades.

The deaths led to fears of renewed unrest in the area, which had been relatively calm for the last several years.

Col. Abdoul Ndiaye said late Saturday that seven others were wounded in the attack, which happened four miles outside the town of Ziguinchor. The military said it had stepped up its presence near the town.

Casamance is separated from the rest of Senegal by the nation of Gambia.

There was no immediate claim of responsibility for the attack.