BAMAKO, Mali (AP) — A weekend attack by militants affiliated to the Islamic State group killed 48 people in the Ménaka region of eastern Mali, a lawmaker told The Associated Press Tuesday.

Fighters from the Islamic State in Sahel Province, or ISSP, attacked on Sunday night into Monday morning and casualties included children and elderly, Moussa Ag Acharatoumane, a Tuareg leader and member of the National Transitional Council, said.

According to Moussa Ag Acharatoumane, the armed group attacked civilians, accusing them of revealing ISSP positions to the Malian army who had been conducting a drone strike on the group.

ISSP operates mostly in the Ménaka region of Mali, where it faces stiff competition from another militant group, Jama’at Nusrat al-Islam wal-Muslimin (JNIM), and in the neighboring countries of Burkina Faso and Niger. It has not claimed responsibility for the attack.

On Monday, the Malian army announced it had located a major base housing “several terrorist elements as well as military equipment and logistical supplies” 65 kilometers (40 miles) southwest of the town of Ménaka.

“After confirming the intelligence gathered and assessing the situation, the site was targeted and successfully struck,” an army statement said.

The vast Sahel region has become the deadliest place in the world for extremism. The military governments of Mali, Burkina Faso and Niger in recent years have struggled to turn the tide of armed attacks in the region despite seizing power and turning to Russia for help.