Rioting has broken out in the northern city of Kano at a rally to protest at the recent killing of hundreds of Muslims in central Nigeria.
Reporters and eyewitnesses have seen at least 10 bodies at the scene.
Thousands of Muslims fled Yelwa during the violence
Some 10,000 Muslims marched to the state governor's office from a mosque to hand over a letter of protest.
More than 10,000 people have died in ethnic, religious and sectarian violence in Nigeria since the end of military rule five years ago.
Reporters said several Christian-run businesses were looted and burned in Kano, with heavily armed officers in police vehicles sporadically firing warning shots.
Many businesses, including a large Christian market, had been shut ahead of the rally.
Tensions have risen in Nigeria in the past week, since members of the Christian Tarok community attacked the mainly Muslim town of Yelwa in the central Plateau State in a dispute over land and cattle.
In Kano, Muslim leaders gave Nigeria's government seven days to act against the Christian militia that carried out the killings "or bear responsibility for whatever happens".
"The Federal Government should put a stop to the killing of Muslims in Plateau State or else the Muslims will have no option but to defend themselves," the leading Islamic cleric in Kano, Ibrahim Kabo, was quoted by Reuters news agency as saying.
The New York-based organisation, Human Rights Watch, had earlier warned of the dangers of violence escalating if concrete measures were not taken against the killers in Yelwa.
They urged the government to bring those responsible for the killings to justice, disarm local militias and deploy an adequate number of police in tense areas.
In 2001, more than 1,000 people died in religious clashes in the Plateau State capital, Jos.
The government set up a commission of inquiry into the violence in Jos, but has still to publish its findings.
The latest violence in Plateau State followed the deaths in February of 48 Christians killed by armed Muslim Fulanis in Yelwa after they had taken refuge in a church.
Muslims are prediominant in the north of Nigeria, with Christians dominating in the south of the country.