The Latest on Nigeria’s election (all times local):

8:15 a.m.

Nigerians have begun voting in a presidential election one week after a surprise last-minute delay blamed on logistical challenges.

Women wait in queue to cast their votes during Presidential and National Assembly election in Yola, Nigeria, Saturday, Feb. (AP Photo/Sunday Alamba)
Women wait in queue to cast their votes during Presidential and National Assembly election in Yola, Nigeria, Saturday, Feb. (AP Photo/Sunday Alamba)

President Muhammadu Buhari has cast his ballot as he seeks a second term in a race that observers now say is too close to call with top challenger and former Vice President Atiku Abubakar.

The ailing Buhari has been criticized for not delivering enough on his promises to tackle insecurity, the economy and corruption. Abubakar points to his business success in making sweeping pledges to turn the economy around but is dogged by corruption allegations.

Gunfire has been heard in at least two cities shortly before the polls opened, but police in Maiduguri in the northeast called the blasts there a show of force by security forces.

Voters line up to cast their votes during Presidential and National Assembly election in Yola Nigeria, Saturday, Feb. (AP Photo/Sunday Alamba)
Voters line up to cast their votes during Presidential and National Assembly election in Yola Nigeria, Saturday, Feb. (AP Photo/Sunday Alamba)

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7:55 a.m.

Multiple blasts in Nigeria’s northeast are opening election day as President Muhammadu Buhari seeks a second term in Africa’s most populous nation.

Voters line up to cast their votes during the Presidential and National Assembly election in Yola Nigeria, Saturday, Feb. (AP Photo/Sunday Alamba)
Voters line up to cast their votes during the Presidential and National Assembly election in Yola Nigeria, Saturday, Feb. (AP Photo/Sunday Alamba)

The blasts in the Borno state capital of Maiduguri came shortly before polls were to open. Police there say it was for “security purposes” and not an attack.

Gunfire also has been heard in parts of Port Harcourt in the restive south, where the military presence is said to be heavier than in past elections.

Buhari in a final address to the nation on Friday vowed that the more than 72 million Nigerians who can vote in this election would be able to go to the polls in peace.

But the Boko Haram extremist group, its Islamic State-affiliated offshoot and various agitators across the country have other plans.