Fighting around the central Nigerian city of Jos continued Saturday, a day after President Umaru Yar'Adua deployed military troops and imposed a night-time curfew. Gilbert da Costa has been monitoring developments from Abuja and filed this report for VOA.

Residents in Jos say sporadic shooting could still be heard on Saturday, and arsonists continued to loot and burn properties.

Government troops are struggling to contain rival ethnic and religious groups armed with guns and machetes.

Some trapped residents have continued to make distress phone calls for help.

Local resident Jude Onwumanan told VOA the fighting seems to be spreading and the security forces are yet to make their presence felt.

"The situation has gotten out of control to the extent that the security agents don't seem to know how to start to handle it. Immediately after the announcement of the result [last night], Hell was let loose and it escalated the problem which started Friday morning. As we are speaking, corpses are being taken to the various hospitals; houses are being pulled down or burnt," Onwumanan said.

The state government announced a 24-hour curfew on Saturday and ordered troops to shoot on sight to enforce the measure.

The unrest is the most serious of its kind in Africa's most populous nation since President Yar'Adua took power in May 2007.

Information Minister John Odey says security forces have been ordered to restore peace quickly.

"The president is sad; the federal government is very, very concerned about the lives and properties in Plateau state. We urge the security agencies in collaboration with the state governor to bring the situation under the control as much as possible," he said.

Red Cross officials say at least 20 people were killed and 300 injured on Friday. Several more would have died on Saturday, eyewitnesses' say. Thousands had taken refuge in government buildings.

The post-election violence was between indigenous Christians and Muslim and Hausa settlers. Rioters torched churches and mosques and burned tires in the middle of the streets.

Hundreds were killed in sectarian street fighting in Jos in 2001. Three years later, hundreds died in clashes in the town of Yelwa, leading then-President Olusegun Obasanjo to declare a state of emergency and impose a curfew.