MAIDUGURI, Nigeria –  A security official says suspected Islamic sect members have ambushed and killed at least 24 members of a youth vigilante group in northeastern Nigeria.

The attack, which occurred Friday when the Civilian Joint Task Force vigilantes were on a mission to find sect members, also left 36 people missing, the official said on condition of anonymity because he is not permitted to speak to the media.

The attack took place near Monguno town, 158 kilometers (98 miles) from the city of Maiduguri, the Borno state capital where the Boko Haram Islamic ideology started years ago.

The official said Saturday that about 100 Nigerians were ambushed by sect members dressed in military uniforms.

Two attacks earlier in the week killed at least 20 vigilantes.