People reported fled violence in villages and blasts were heard in the city of Maiduguri. Boko Haram had warned people not to vote.
Some polling stations were slow to open Saturday in an already delayed election as Nigeria’s young population cast their ballots for the next president of Africa's biggest economic power amid pockets of militant violence.
Nigeria Elections: Gov't Calls for Trust in Security Forces
President Muhammadu Buhari and his main challenger, businessman Atiku Abubakar, cast their ballots in Nigeria's presidential election as voting began after a week's delay. Analysts said the vote is too close to call, and that the outcome set to hinge on which man voters most trust to revive an economy that is still struggling to recover from a 2016 recession.
Buhari, a former military ruler who was later elected president, is seeking a second term in charge of Africa's most populous nation and top crude producer. Atiku, a former vice president, has pledged to expand the role of the private sector. The two candidates are the donimant names in a race of over 70 candidates.
In the country's northeast, where insurgent groups like Boko Haram and Islamic State group have waged a 10-year war, blasts were heard in the city of Maiduguri, the capital of Borno state, witnesses told Reuters. Boko Haram had warned people not to vote.
Residents in the village of Geidam in Yobe state, which neighbors Borno, said they fled an attack by suspected militants.
"We have along with our wives and children and hundreds of others fled. We are right now running and hiding in the bushes," Geidam resident Ibrahim Gobi said.
Colonel Sagir Musa, acting director of army public relations, said there had not been an attack on any part of Maiduguri, where activity had been part of an exercise by the military. Musa added that there was an attack on a security outpost in Geidam however there were no casualties.
Security sources told Reuters that militants had struck at parts of the city and a witness said he had heard gunshots and Nigerian air force jets were flying overhead.
Last Saturday, the election was postponed around five hours before polling stations were due to open by electoral commission, which cited logistical factors.
However, several polling stations across the country were slow to open for the official election day, and others reported problems with machines meant to verify voters cards, Reuters witnesses said. The country has 72.8 million eligible voters.
"I’ve been to 10 polling units today. I’ve been redirected many times," said Victor Kanoba a voter in Lagos.
John Tomaszewski, an observer with the joint United States National Democratic Institute and International Republican Institute delegation, said delays had been somewhat expected given the logistical challenge of getting materials to the polling stations in time for the opening.
Buhari, who voted in his hometown of Daura in the northern state of Katsina, said: "I will congratulate myself, I'm going to be the winner" when asked by reporters if he would congratulate his rival, should Atiku win the election.
Atiku later cast his ballot in the eastern Adamawa state, saying shortly after voting, "I look forward to a successful transition."
Polls closed at 2:00 p.m. local time. At the time of writing, no winner had been announced.