An attack by insurgents killed 19 Burkina Faso military police and a civilian on Sunday in the tri-border northern region where the West African nation is battling Islamist militants, Security Minister Maxime Kone said.

Kone said the toll was provisional.

“This morning a detachment of the gendarmerie suffered a cowardly and barbaric attack. They held their position,” Kone said on national television, adding that 22 survivors had been found.

The attack on a military police outpost near a gold mine in Inata came two days after another attack in which seven police were killed in the area near Niger and Mali.

Islamist militant groups linked to al Qaeda and Islamic State are active in the tri-border area where several nations including France, Chad, Niger, Mali and Burkina Faso have deployed hundreds of troops.

Two Burkina Faso security sources and a diplomatic source said earlier on Sunday that at least 30 military police were killed in the attack and the toll could be higher, making it one of the deadliest attacks on Burkina Faso troops.

Burkina Faso’s armed forces confirmed the Sunday attack in a statement saying “a gendarmerie detachment was the subject of a terrorist attack”. It did not provide further details.