OUAGADOUGOU—Unknown assailants killed 44 people in two attacks in northern Burkina Faso overnight on Thursday, authorities said.

The raids occurred in the villages of Kourakou and Tondobi in the Sahel region of the West African country, an area overrun by groups linked to al-Qaeda and ISIS terrorist groups that have carried out repeated attacks for years.

It is not clear which group carried out Thursday’s attacks. Authorities on Saturday blamed “armed terrorist groups”.

More than 2 million people are displaced and thousands have been killed by the violence in Burkina Faso, one of the world’s poorest countries.

The unrest triggered two coups last year by the military, which has vowed to retake control of the country but has failed to stem the bloodshed.

Unrest in the region began in Mali in 2012, when Islamists hijacked a Tuareg separatist uprising. The violence has since spread into neighboring Burkina Faso and Niger and threatens to destabilize coastal countries further afield.