Violence has flared for a second day in the northern Nigerian city of Kano despite a huge security presence.
Soldiers and police have the city centre under control
Riots spread to suburbs not secured by police, after an overnight curfew was lifted. Police say 10 people have died but other reports have higher figures.
Thousands of people have fled their homes after Muslim youths went on the rampage burning homes and vehicles.
They are demanding that the government take action after a massacre of Muslims last week by a Christian militia.
Islamic leaders in the mainly Muslim town of Kano have joined Nigeria's president in urging calm.
More than 10,000 people have been killed in ethnic, religious and political violence in the country since the end of military rule in 1999.
Eyewitnesses say that large mobs of young men were specifically targeting Christians, however this was denied by Kano's police commissioner.
But thousands of Christians have been fleeing Kano's suburbs, including Sharada industrial district, seeking safety.
"Many people have been killed in Sharada, but we have not been able to bring out their bodies, because we had to look to our own lives," 37-year-old foundry worker Joshua Adamu told AFP news agency.
The mob violence was sparked by a peaceful protest on Tuesday against the recent killing of hundreds of Muslims at the hands of Christian militants in central Plateau State.
The demonstration was called to issue a seven-day ultimatum to President Olusegun Obasanjo to deal with the situation or face the consequences.
Tension has spread to other parts of the mainly Muslim north.
In Kaduna, security has been beefed up, with some 40 different groups holding discussions about security with the state governor.
In Bauchi State, the governor has assured Christian groups of their safety after leaflets were distributed given them until Friday to leave the state.
President Obasanjo told Muslim clerics in the capital Abuja. "I will appeal to you to restrain our Muslim brothers... because if you go for an eye for an eye, this country will be bloody."
A leading Kano Muslim cleric, Ibrahim Kabo, has urged the federal government to prevent further killings of Muslims in Plateau.
Mr Kabo warned that if the government did not act, Muslims would "have no option but to defend themselves".
Helen James, aged 40, said that their housing estate had been "totally burned."
"My husband and his brother have been badly hurt, they have so many knife wounds in their back. They have been taken to the hospital. We don't know whether they are dead or alive," she wept.
Reuters news agency reports that some members of the Christian minority gathered in the central Sabon Gari (foreigners' town) district and burned a mosque in retaliation for the burning of several churches by Muslims on Tuesday.
"A lot of people in Sabon Gari are armed with guns and machetes daring the Muslim militia to attack," eyewitness Jackson Kentebe said.
"Everywhere, people have taken the laws into their own hands," said Abdul Damini Daudu, a police official.
Nigeria's combined Christian and animist communities are roughly equal in size to its Muslim population, with the Christians living predominately in the south.