At least 10 people have been killed after a bomb exploded in the northeast Nigerian city of Maiduguri, a region where the armed group Boko Haram is active.
The bomb went off at around 6 pm (1700:GMT) in a busy market area in Ajilari-Gomari near the city's airport, two
witnesses and a police source said.
"I am at the scene now, it is very bad," local resident Ismaila Abdulraman told the Reuters news agency by telephone.
"Many men, women and children died. The fire service are on the ground now and they are bringing corpses of people and trying to put out the fire at the scene," Abdulraman added, saying he had already seen 10 bodies.
The final death toll was likely to be higher because dozens of people were trapped in the rubble, the witnesses said.
There was no immediate claim of responsibility for thebombing, but Boko Haram only communicates occasionally through Internet videos, days or weeks after attacks.
The group, whose fight to introduce Islamic law in northern Nigeria has killed thousands and made the group the biggest threat to security in Africa's top oil producer, is increasingly targeting the civilian population.
The military and police did not immediately respond to requests for official comment.
Setback for president
President Goodluck Jonathan started an intensified military push to end Boko Haram's four-and-a-half year insurgency almost a year ago but the bloodshed has not diminished.
He is expected to run in a closely contested election next year.
The violence has been largely contained to Nigeria's remote northeastern rural areas on the borders with Cameroon and Niger, far from commercial hubs such as Lagos and Abuja, and from the southern oil fields.
The attack in Maiduguri, the northeast's biggest city, marks a setback for Jonathan's military campaign.
"The insurgents targeted a busy area where they knew many people usually visit in the evening for commercial activities," a policeman, who asked not to be named, said. "It appears Boko Haram are in the city again."
Dozens of school children were shot or burned to death in a rural region near the northeastern city of Damaturu last week.
More than 300 people, mostly civilians, were killed last month, including in two other attacks that killed about 100 each, one in which a a village was razed and panicked residents shot as they tried to flee.
Western governments are concerned about Nigerian groups such as Boko Haram linking up with al-Qaeda-linked cells in
other countries in the Sahel region, such as Mali, where France sent troops a year ago to oust fighters there, reuters reported.