A group of Nigerians armed with guns and machetes has killed hundreds of people, including women and children, in a number of villages near the central city of Jos.
Local villagers - predominantly Christian - blame Muslims for the attack.
Clashes between the two communities are not uncommon due to a historical feud over control for the region's fertile farmland.
Human rights groups say poor governance and a lack of accountability have exacerbated the conflict.
But Goodluck Jonathan, Nigeria's acting president, has responded to the latest violence by ordering his security forces to hunt down the killers and bring order to the region.
Al Jazeera's Harry Fawcett reports from Nigeria.
Source: Al Jazeera