Supporters of the presidential candidate Muhammadu Buhari and his All Progressive Congress hits with a motorbike another supporter during celebrations in Kano March 31, 2015. Nigeria's opposition APC declared an election victory on Tuesday for former military ruler Buhari and said Africa's most populous nation was witnessing history with its first democratic transfer of power. (Photo by Goran Tomasevic/Reuters)

Supporters of opposition candidate Muhammadu Buhari, one bound in mock chains, celebrate an anticipated win for their candidate, in Kano, Nigeria Tuesday, March 31, 2015. Nigeria's aviation minister says President Goodluck Jonathan has called challenger Muhammadu Buhari to concede and congratulate him on his electoral victory, paving the way for a peaceful transfer of power in Africa's richest and most populous nation. (Photo by Ben Curtis/AP Photo)

A puppet showing Presidential challenger Muhammadu Buhari is set at an intersection in Kaduna, Nigeria Monday, March 30, 2015. Nigerians are waiting in hope and fear for results of the tightest and most bitterly contested presidential election in the nation's turbulent history. Placard reads “He is the one god willing”. (Photo by Jerome Delay/AP Photo)

Residents celebrate the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria Tuesday, March 31, 2015. The spokesman for retired Gen. Muhammadu Buhari says the former military dictator has won Nigeria's bitterly contested presidential election but fears “tricks” from the government. Garba Shehu told The Associated Press that their polling agents across the country tell them they have succeeded in defeating President Goodluck Jonathan”. (Photo by Jerome Delay/AP Photo)

Supporters of opposition candidate Gen. Muhammadu Buhari's All Progressives Congress (APC) party celebrate by wheel-spinning motorcycles what they said was the senatorial win in Kano Central district of APC candidate Rabiu Musa Kwankwaso, in Kano, northern Nigeria Monday, March 30, 2015. Nigerians are waiting in hope and fear for results of the most tightly contested presidential election in the nation's turbulent history. (Photo by Ben Curtis/AP Photo)

Nigerian policemen gather around a shop with a television set in Kaduna, Nigeria on Monday, March 30, 2015, to watch the beginning of the live broadcast of the collation of votes for last Saturday's elections. (Photo by Jerome Delay/AP Photo)

Residents celebrate the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

A young Nigerian girl walks past election posters, some showing presidential candidate, Muhammadu Buhari, in Kaduna, Nigeria Monday, March 30, 2015. (Photo by Jerome Delay/AP Photo)

Supporters of opposition candidate Muhammadu Buhari celebrate an anticipated win for their candidate, in Kano, Nigeria Tuesday, March 31, 2015. Nigeria's aviation minister says President Goodluck Jonathan has called challenger Muhammadu Buhari to concede and congratulate him on his electoral victory, paving the way for a peaceful transfer of power in Africa's richest and most populous nation. (Photo by Ben Curtis/AP Photo)

Supporters of opposition candidate Muhammadu Buhari look on as a three-wheeled passenger taxi, driving wildly in celebration of an anticipated Buhari win, screeches to a halt after flipping over on its side while driving in Kano, Nigeria Tuesday, March 31, 2015. (Photo by Ben Curtis/AP Photo)

Supporters of opposition candidate Gen. Muhammadu Buhari's All Progressives Congress (APC) party celebrate what they said was the senatorial win in Kano Central district of APC candidate Rabiu Musa Kwankwaso, in Kano, northern Nigeria Monday, March 30, 2015. (Photo by Ben Curtis/AP Photo)

Nigerians celebrate the anticipated victory of Presidential candidate Muhammadu Buhari by doing a burnout on a scooter in Kaduna, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

Supporters of opposition candidate Gen. Muhammadu Buhari's All Progressives Congress (APC) party celebrate what they said was the senatorial win in Kano Central district of APC candidate Rabiu Musa Kwankwaso, in Kano, northern Nigeria Monday, March 30, 2015. (Photo by Ben Curtis/AP Photo)

A supporter of opposition candidate Muhammadu Buhari riding on a motorcycle scrapes a machete on the ground to create sparks and noise, in celebration of an anticipated win for his candidate, in Kano, Nigeria Tuesday, March 31, 2015. (Photo by Ben Curtis/AP Photo)

Residents celebrate the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria, Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

Supporters of opposition candidate Muhammadu Buhari celebrate an anticipated win for their candidate, in Kano, Nigeria Tuesday, March 31, 2015. (Photo by Ben Curtis/AP Photo)

Supporters of opposition candidate Muhammadu Buhari riding on a motorcycle celebrate an anticipated win for their candidate, in Kano, Nigeria Tuesday, March 31, 2015. (Photo by Ben Curtis/AP Photo)

Residents celebrate the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

A supporter of the presidential candidate Muhammadu Buhari and his All Progressive Congress (APC) party celebrates on his bicycle in Kano, March 31, 2015. (Photo by Goran Tomasevic/Reuters)

Residents celebrate the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

A Nigerian man carrying a dummy of President Goodluck Jonathan on his back joins others as they celebrate the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

Nigerians celebrate the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

Supporters of opposition candidate Muhammadu Buhari celebrate an anticipated win for their candidate, in Kano, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

Residents celebrate the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

Residents celebrate the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

An ambulance races through Nigerians celebrating the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

Residents celebrate the anticipated victory of Presidential candidate Muhammadu Buhari in Kaduna, Nigeria Tuesday, March 31, 2015. (Photo by Jerome Delay/AP Photo)

Supporters of the presidential candidate Muhammadu Buhari and his All Progressive Congress (APC) party celebrate in Kano, March 31, 2015. (Photo by Goran Tomasevic/Reuters)