The French presidency said three French soldiers were killed Monday in Mali when an improvised explosive device hit their armored vehicle.

The soldiers were participating in a military operation in the Hombori area of Mali’s central Mopti province, part of a larger mission aiming at fighting Islamist extremists in Africa’s Sahel region, the French presidency said in a statement.

Defense Minister Florence Parly said the soldiers were working “in an area where terrorist groups are attacking civilians and threatening the regional stability.” Parly said they were involved in a mission aiming at helping Mali to gradually be able to ensure its own security. The defense minister did not provide further details.

France has more than 5,000 troops deployed in West Africa to help fight extremist groups as part of Operation Barkhane.

French President Emmanuel Macron paid tribute “with the greatest respect” to the three soldiers who died. He cited France’s determination to “pursue the fight against terrorism” in the region.

Islamic extremist rebels were forced from power in northern Mali after a 2013 French-led military operation. The rebels regrouped in the desert and now launch frequent attacks on the Malian army and its allies.