GUSAU, Nigeria — Tijani Idris heard the roar and rushed inside his home, peeking through the window to spot fighter jets crisscrossing the sky above his forest village.

They were Nigerian Air Force jets, scrambled to battle yet another major security threat in one of Africa’s most populous nations: groups of armed gangs that have made the northwestern corner of the country their haven.

This year alone in the state of Zamfara, hundreds have died in mass murders and more than 21,000 people have been forced from their homes. In total, officials say at least 2,000 people have died from violence in the area since 2011.

Earlier this month, the president responded with force, sending 1,000 troops and jets to fight the gangs.