MAIDUGURI, Nigeria (AP) — Suspected Islamic extremists bombed a major bridge on a northeast Nigerian highway, further limiting access to base camps in the Sambisa Forest where scores of kidnapped girls are believed to be held captive, witnesses and the leader of a group fighting Boko Haram said Monday.

Gunmen destroyed most of the bridge on the road between Maiduguri and Biu on Saturday night, the spokesman for the Nigerian Vigilante Group, Abbas Gava, told The Associated Press.