MAIDUGURI, Nigeria (AP) -- A car bomb in a marketplace in Maiduguri, the northeast Nigerian city that is the birthplace of Boko Haram extremism, killed at least 56 people on Tuesday, the leader of a civilian group that recovered the bodies said.
Sadiq Abba Tijjani, leader of the Civilian Joint Task Force, told the Associated Press his group recovered at least 56 dead bodies at the blast site, mostly elderly women who sold peanuts and lemon juice at the market.
Tijjani said they managed to identify 21 of the dead but the rest "were either burnt or damaged beyond recognition."
Other witnesses also estimated the death toll to around 50. Some officials said only 17 people died in the explosion that ripped through the market early Tuesday, but officials regularly play down the death toll.
Witnesses and officials blamed Boko Haram extremists who have been accused of a series of bomb attacks in the West African nation. The group, which attracted international attention with its April abduction of more than 200 schoolgirls, has scaled up its activities in recent months, launching more frequent and deadly attacks.
The inability of the military to curb attacks has brought international criticism, with the United Nations noting the government is failing in its duty to protect citizens. In a statement issued Monday, U.N. Secretary-General Ban Ki-moon reiterated the readiness of the United Nations "to support Nigeria as it responds to this challenge in a manner consistent with its international human rights obligations."
Maiduguri, a city of more than 1 million people, has suffered from many strikes. In March, twin car bombs killed more than 50 people at a late-night market where people were watching a football match on a big screen.
Tuesday's explosives were hidden under a load of charcoal in a large vehicle, according to witnesses who spoke on condition of anonymity for fear of reprisals.
Stalls, goods and vehicles were reduced to piles of trash. The burnt-out shells of five vehicles and some tricycle taxis marked the site of the explosion.
Trader Daba Musa Yobe, who works near the popular market, said the bomb went off just after the market opened at 8 a.m., before most traders or customers had arrived.
Witnesses said the death toll could have been even higher was it not for Ramadan, the Muslim month of fasting from sunrise to sunset, which meant fewer people than normal were at the market at that time because they had stayed up late to eat.
Security forces cordoned off the area for five hours but had a hard time keeping people out, even though they warned there could be secondary explosions timed to target rescue efforts.
Boko Haram has adopted a two-pronged strategy this year of bombing urban areas and conducting scorched-earth attacks in northeastern villages where people are gunned down and their homes burned.
On Sunday, suspected extremists sprayed gunfire on worshippers in four churches in a northeastern village and torched the buildings, killing at least 30 people.
Last week, at least 42 people were killed in three blasts around the country, including 24 people at the biggest shopping mall in Nigeria's central capital Abuja. It was the third blast in as many months in that city. In May, twin car bombs at a marketplace also left more than 130 dead in the central city Jos.
Nigeria's military announced Monday night that it had busted a terrorist intelligence cell and arrested a businessman who "participated actively" in the mass abduction of schoolgirls that caused outrage around the world.
It was unclear if the first arrest of a suspect in the kidnappings could help in rescuing the at least 219 girls who remain captive. Boko Haram is threatening to sell the girls into marriage and slavery if Nigeria's government does not exchange them for detained insurgents.
Nigeria's President Goodluck Jonathan on Monday condemned the recent attacks.
"The federal government and national security agencies will continue to intensify ongoing efforts to end Boko Haram's senseless attacks until the terrorists are routed and totally defeated," he said in a statement.
Faul reported from Lagos, Nigeria.
Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.