A man throws a container of water towards a burning car after a bomb exploded minutes after Nigerian President Goodluck Jonathan left Gombe stadium, February 2, 2015.

The bomb exploded about 200 meters from the stadium, engulfing the car in flames and killing at least one bystander and wounding seven.

People gather to help at the scene of a bomb explosion in Gombe, Nigeria, February 2, 2015.

Smoke rises after a suicide bomb explosion in Gombe, Nigeria, February 1, 2015, a day ahead of Nigeria's President Goodluck Jonathan's visit to the state for an election campaign rally.

An army truck is seen driving along Mubi-Yola road in Jimeta, Adamawa state, January 31, 2015.

Men on camels cross the water as a woman washes clothes in Lake Chad in Ngouboua, Chad, January 19, 2015.

Refugees fleeing attacks by Islamist militant group Boko Haram continued to cross the border into neighboring Chad on Monday. According to United Nations and government figures, some 20,000 Nigerians had fled to Chad, Niger and Cameroon in the two weeks prior to January 13 after their towns and villages were attacked.

A girl displaced as a result of Boko Haram attack in the northeast region of Nigeria, rests her head on a desk at Maikohi secondary school camp for internally displaced persons in Yola, Adamawa State, Nigeria, Jan. 13, 2015.

Boko Haram says it is building an Islamic state that will revive the glory days of northern Nigeria's medieval Muslim empires, but for those in its territory life is a litany of killings, kidnappings, hunger and economic collapse.

Children displaced as a result of Boko Haram attacks in the northeast region of Nigeria, cheer at a camp for internally displaced persons in Yola, Adamawa State, Nigeria, Jan. 13, 2015.

People fleeing Boko Haram violence in the northeast region of Nigeria, cook food at Maikohi secondary school camp for internally displaced persons in Yola, Adamawa State, Nigeria,  Jan. 13, 2015.

People displaced as a result of Boko Haram attacks in the northeast region of Nigeria, are seen near their tents at a faith-based camp for internally displaced people in Yola, Adamawa State, Nigeria, Jan. 14, 2015.

Women displaced as a result of Boko Haram attacks in the northeast region of Nigeria, sit together at a camp for internally displaced people in Yola, Adamawa State, Nigeria, Jan. 13, 2015.

Boko Haram says it is building an Islamic state that will revive the glory days of northern Nigeria's medieval Muslim empires.

Morris Enoch, a leader of traditional militia hunters helping the army to fight the Boko Haram insurgence in the northeast region of Nigeria, speaks during an interview in Yola, Adamawa State, Nigeria, Jan. 14, 2015.

Nigerian security inspect the scene of a bomb blast at the Jos Terminus Market, on December 12, 2014. A double bomb attack that killed 31 people in a crowded market in the central Nigerian city of Jos was likely to have been carried out by Boko Haram, the state government said. "It's an extension of the terrorist acts that have been penetrating all states and cities," Pam Ayuba, spokesman for the Plateau state governor Jonah Jang, told AFP by telephone.

Satellite image of the village of Doro Baga, or Doro Gowon, in north-eastern Nigeria taken on January 2, 2015. Image shows an example of the densely packed structures and tree cover.

Satellite image 2, taken on  January 7, 2015, shows almost all of the structures razed.

The red areas indicate healthy vegetation.

Two  images of Baga, Nigeria, show the aftermath of an attack.

One image was taken on January 2, 2015. Many thatch roof structures are visible. These have been rebuilt since the attack on Baga in April 2013.

2) Image of Baga taken on January 7 which show many of the thatch roof structures have been razed.

The dark color represents burned areas, while the red indicates heathy vegetation.

A satellite image from Jan. 7, 2015, shows almost all of the structures in the northeast Nigerian town of Doro Baga razed after an attack by Boko Haram militants. The inset demonstrates the level of destruction of most structures in the town. The red areas indicate healthy vegetation.

A band of hunters pose in Yola, state capital of Adamawa, on December 4, 2014 after taking part in an operation against Nigerian Islamist extremist group Boko Haram.

Military and vigilantes forces acknowledge the crucial support of hunters in the fight against Boko Haram.

A billboard bearing the name of one of the missing Chibok schoolgirls, Ruth Ngladar, is tied to a fence in Ikoyi, in Lagos, Nigeria, Dec. 17, 2014.

A man injured in a suicide blast is carried on a mattress by relatives at the General Hospital in northeast Nigerian town of Potiskum, January 12, 2015. Four people were killed and 46 injured when two female suicide bombers detonated their explosives outside a mobile phone market in the town on January 11, 2015. Although no one claimed responsibility the attacks bore the hallmark of Boko Haram Islamists who have been increasingly using female suicide bombers in their armed campaign to establish a hardline Islamic state.

Potiskum, the commercial hub of Yobe state has been repeatedly attacked by Boko Haram.

A crowd gathers around the remains of a suicide bomber at a scene of multiple bombings at Kano Central Mosque, Nov. 28, 2014.

Gunmen set off three bombs and opened fire on worshippers at the central mosque in north Nigeria's biggest city Kano, killing at least 100 people in an attack that bore the hallmarks of Islamist Boko Haram militants.

A crowd gathers at a scene of multiple bombings at Kano Central Mosque, Nov. 28, 2014. Gunmen set off three bombs and opened fire on worshippers at the central mosque in north Nigeria's biggest city Kano, killing at least 100 people in an attack that bore the hallmarks of Islamist Boko Haram militants.

Security and emergency agency staff investigate the Kano Central Mosque bombing scene in Kano, Nigeria, Nov. 29, 2014.

Gunmen set off three bombs and opened fire on worshippers at the main mosque in north Nigeria's biggest city Kano, killing at least 100 people.

Security and emergency agency staff investigate the Kano Central Mosque bombing scene in Kano, Nigeria, Nov. 29, 2014.

Gunmen set off three bombs and opened fire on worshippers at the main mosque in north Nigeria's biggest city Kano, killing more than 100.

The Emir of Kano, Muhammed Sanusi II, leads evening prayers at Kano Central Mosque as part of his visit to inspect the premises in Kano, Nov. 29, 2014. A total of 100 people were killed in Friday's coordinated attack on the central mosque of north Nigeria's biggest city of Kano. The targeted mosque is next to the palace of the emir of Kano, who is the second highest Islamic authority in Africa's most populous country and a vocal critic of Boko Haram.

The Emir of Kano, Muhammed Sanusi II, center, inspects the Kano Central Mosque after evening prayers in Kano, Nov. 29, 2014.

The Emir of Kano, Muhammed Sanusi II, touches the hand of a victim of the Kano Central Mosque bombings at the Murtala Mohammed Specialist Hospital in Kano, Nov. 30, 2014.

Dauda Iliya, spokesperson for the Chibok community in Abuja, speaks during a meeting to review efforts to recover the abducted Chibok girls organised by the Chibok Community Association in collaboration with the #BringBackOurGirls group, in Abuja,  Nigeria, Jan. 1, 2015.

Parents of 200 Nigerian schoolgirls kidnapped by Islamist Boko Haram rebels in April said they were appealing directly to the United Nations for help after losing hope that the Nigerian government would rescue them.

Rebecca Samuel, right, mother of Sarah, one of the abducted Chibok schoolgirls, reacts while speaking at a meeting to review efforts to recover the abducted Chibok girls organized by the Chibok Community Association in collaboration with the #BringBackOurGirls campaign, in Abuja, Nigeria, Jan. 1, 2015.

Parents of 200 Nigerian schoolgirls kidnapped by Islamist Boko Haram rebels in April said they were appealing directly to the United Nations for help after losing hope that the Nigerian government would rescue them. Picture taken January 1, 2015.