Unknown assailants killed 40 people and wounded 33 others in an attack on the army and volunteer defense forces in northern Burkina Faso, the government said in a statement today.

The attack took place yesterday in the village of Aorema near the town of Wahiguya in the Northern Region, not far from the border with Mali, an area where Islamist groups linked to al-Qaeda and the Islamic State have a large presence and have been launching attacks for years.

It is unclear which organization carried out the attack. It comes nine days after gunmen killed 44 people in the villages of Kuraku and Todobi in the north of the West African country.

Six soldiers and 34 members of a volunteer defense force were killed in yesterday’s attack, the statement said. The government has urged citizens to join local defense forces in an effort to counter eight years of violence that have killed thousands and forced millions from their homes.

Unrest in Burkina Faso has led to two coups in the past year by the military, which vowed to regain control of the country but failed to stop the attacks.

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