The governor of Nigeria's Gombe state imposed a 24-hour curfew in response to a Boko Haram attack that sparked raging gunfire Saturday.
The governor's spokesman said that although the fighting was taking place in Gombe city, the curfew applied across the entire state, which shares the same name. He said residents were to remain indoors until further notice, as security forces tried to track down the gunmen and restore order.
There was no word on casualties.
Some reports said the siege was over, and that the gunmen had fled with the bodies of their dead and wounded.
Reports from the area said the militants circulated a letter warning residents not to come out for the upcoming general elections, which had been scheduled for Saturday but have been postponed six weeks because of security concerns.
In Saturday's letter, the militants promised to attack all polling centers during the elections. It called on Muslim residents to stay home for their own safety.
On Friday, Nigerian President Goodluck Jonathan told The Wall Street Journal that he had been asking the United States for more help to fight Boko Haram.
Jonathan told the newspaper that the militants were receiving training and funds from Islamic State, the jihadist group operating in Iraq and Syria. According to the article, he said the United States was a friend who is fighting the same Islamist forces and should aid Nigeria with combat troops.
Pentagon spokesman Rear Admiral John Kirby said there were no plans to unilaterally send U.S. troops to Nigeria. However, he said, discussion is beginning on formation of a multinational task force that the international community is working with certain African nations to establish.
On Friday, Boko Haram, for the first time carried out an attack in Chad, part of a widening insurgency that has now drawn in four countries.
Chadian officials say at least 12 people were killed during the early morning violence in the village of Ngouboua, including the village chief. Officials say the militants crossed Lake Chad in four motorized boats early in the morning.
The militants set fire to parts of the village before being driven out by Chadian troops.
Officials say the army could not follow the attackers because it lacks motorized boats, but that Chadian helicopters launched strikes over the lake, destroying the boats of the retreating militants.
The governor of Chad's Lake Region, Bayana Kossingar, said those killed in the fighting included two soldiers, five civilians and five militants.
Ngouboua is already home to more than 2,000 refugees who had fled Boko Haram violence in Nigeria. The head of the refugee camp in Ngouboua, Idriss Peve, says none of the refugees was harmed in Friday's attack.
Boko Haram has previously launched deadly attacks on towns in Cameroon and Niger.
Those two countries along with Chad recently joined a regional offensive against the Islamist extremist group.
The U.N. special representative for West Africa, Mohammed Ibn Chambas, said Friday the United Nations expects Nigeria's military to do more to combat Boko Haram fighters.
Diffa 'virtually empty'
Also Friday, the U.N. refugee agency said the town of Diffa in southeastern Niger is "virtually empty" after several days of clashes between Boko Haram and soldiers from Niger and Chad. Spokesman Adrian Edwards said that before the attacks, Diffa had a population of 50,000.
The agency said violence in northeastern Nigeria has now caused more than 157,000 people to flee to neighboring countries and displaced almost 1 million inside Nigeria.
Nigeria, Niger, Chad, Cameroon and Benin recently agreed to create a regional force of 8,700 troops to fight Boko Haram.
The extremists have killed thousands of people since launching their insurgency in 2009 and control dozens of towns in northeastern Nigeria.