Nigerian officials imposed a dusk-to-dawn curfew Sunday in the northern Nigerian city of Bauchi following clashes over places of worship. Hundreds of troops and police have been deployed to restore order after a day of rioting. Gilbert da Costa reports from Abuja.

Police spokesman in Bauchi, Mohammed Barau, told VOA Sunday calm has returned to the city after security forces moved in to stop the spread of violence.

"The situation now is calm. Everybody is doing his normal business; the affected area is being covered by security personnel-mobile, conventional police, military and other agencies. For now, the situation has returned to normal," said Barau. "Even the state government has imposed a curfew between six in the evening and six in the morning."

Residents say Muslim youths attacked Christians and burned churches in reprisals over the burning of two mosques overnight in the city.  Muslims blamed the fires on Christians. The Red Cross says at least four people have been killed and 28 injured in the clashes.

Northern Nigeria is predominantly Muslim but there are significant Christian communities in the region.

The region was hit by religious and political violence in November that killed hundreds of people in the central city of Jos.

Presidential spokesman Olusegun Adeniyi told reporters President Umaru Yar'Adua has ordered the military to contain the violence.

Nigeria's 140 million people are split almost equally between Muslims and Christians. Analysts say religious violence is a major challenge for the government of President Umaru Yar'Adua, who came to power in 2007 elections that were criticized by international observers.