Militants attacked a town in northern Burkina Faso and killed 35 civilians, most of them women, President Roch Marc Christian Kabore said on Tuesday.
A large group of militants attacked simultaneously the military detachment and civilians in Arbinda, province of Soum, the army said in a statement.
The violence lasted for several hours, according to the military statement.
Army said seven soldiers and 80 militants were killed as the army repelled Tuesday's attack.
President Kabore declared two days of national mourning in the landlocked West African country.
Earlier this month, at least 14 people were killed after gunmen opened fire inside a church in eastern Burkina Faso. Militant attacks have increased in Burkina Faso since 2015.
A number of Islamic extremist groups are known to operate in Burkina Faso, and attacks are frequent in the area.