The attack is one of the worst to occur in Senegal's southern region in recent years. The army says it is not clear whether the gunmen were members of the separatist Movement of Democratic Forces for Casamance (MFDC).
Gunmen killed at least 13 people and injured seven in the Bayotte forest in Senegal's southern Casamance region on Saturday, according to the country's military.
The victims were collecting wood when they were attacked some 7 kilometers (4 miles) from the regional capital Ziguinchor, army spokesman Abdoul Ndiaye said late on Saturday.
The attack is one of the worst to occur in recent years in Casamance, an area separated from the richer northern regions of Senegal by The Gambia.
Armed conflict between separatist rebels known as the Movement of Democratic Forces for Casamance (MFDC) and the government had afflicted the region intermittently for over three decades until both sides signed a ceasefire in 2014.
"It is too early to say whether the attackers were members of the MFDC, the inquiry will tell us that," said Ndiaye. "There had been no tensions lately, no warning signs."
The spokesman said the army had deployed 150 troops to help the victims and locate the gunmen.
Internationally mediated peace negotiations had led the army to release two MFDC fighters hours before the attack.
Senegalese President Macky Sall used his New Year's address last week to call on the MFDC to continue negotiations with the government toward a final peace settlement.
The MFDC sees Casamance as culturally distinct from the rest of the country and has accused the central government of ignoring the region.
Read more: Eight killed during Senegal football match
amp/msh (AFP, AP, Reuters)