Soldiers are patrolling the streets in northern Nigeria as aid workers begin to assess the toll from rioting against President Goodluck Jonathan's election victory.
The Red Cross said many people were killed, hundreds injured and thousands displaced in protests across northern Nigeria by supporters of former General Muhammadu Buhari, who say the election result was rigged.
Churches, homes and shops were razed on Monday and shooting reportedly continued into Tuesday morning.
Rescue workers said they had been unable to reach the worst-affected neighbourhoods and could not yet give a death toll.
Thousands of people are reported to have fled their homes.
Mr Jonathan has imposed a curfew and appealed for an end to the violence.
The electoral commission says he received about 57% of the vote with 22.5 million votes compared to 12.2 million votes for General Buhari.
International observers said the election was reasonably free and fair.
Red Cross volunteers have treated 368 people, some of whom have been taken to hospital.