Troops are patrolling the streets of the central Nigerian city of Jos as aid workers count the dead following clashes between Christians and Muslims.
As many as 500 people are now believed to have died. Three predominantly Christian settlements are reported to have come under attack from Muslim herders.
The raids are thought to have been reprisal attacks after sectarian violence in January in which hundreds died.
The latest unrest in the centre of Africa’s most populous nation comes at a difficult time for Acting President Goodluck Jonathan.
Plateau state lies at the crossroads of Nigeria’s Muslim north and Christian south where competition for control of fertile farmlands between indigenous groups and settlers from the north have repeatedly triggered unrest over the past decade.
A Red Cross spokesman says the security situation in outlying areas remains in disarray.
The herders are said to have fired shots in the air and then cut down their victims with machetes as they fled their homes.