|Farmer in Ivory Coast's Duekoue cocoa plantation|
Army spokesman Jules Yao Yao says 64 others were wounded in the attack early Wednesday outside the town of Duekoue.
He says the victims were shot, stabbed or burned to death. Witnesses say they were all members of the ethnic Guere tribe.
It is not clear what sparked the attack. However, clashes between indigenous tribes and migrant farm workers are common in the region. Tensions between the groups have been exacerbated by Ivory Coast's civil war, which began in 2002.
The United Nations peacekeeping mission in Ivory Coast says it has sent patrols to the region to investigate.
Some information for this report provided by AP and Reuters.