A curfew has been imposed in Bauchi in northern Nigerian after at least 13 people were killed in a sectarian riot.
It began as an argument between a teacher and a pupil over the confiscation of a Koran in school.
But rumours swept the city that the book had been desecrated and that was the cue for youths, some armed with machetes, to rampage in the streets.
The violence comes just two days after protests against Danish cartoons in two northern cities left at least 25 dead.
Reports say two churches were burnt in Bauchi before police fired tear gas and live rounds to disperse the crowd.
The state governor and senior security officials in the state are meeting to discuss security and consider whether to hold an inquiry into the incident.
The Red Cross say they have recovered 13 bodies but this may rise as they hope to recover more bodies.
The riot was not directly related to the violence over the weekend in the two northern towns of Maiduguri and Katsina, which began as demonstrations against the Danish cartoons of the Prophet Mohammed.
But Nigeria is going through a period of civil disturbance, with riots in the north and militant activity in the southern Niger Delta .
The BBC's Alex Last in Abuja says there is speculation that the instability is linked to the question of whether the Nigerian president will try to change the constitution and stand for a third term.
Public hearings on constitutional reform are due to begin on Wednesday.