Nigeria counts votes in closely-fought presidential election even as voting continues in some units where polling opened late or ballot machines malfunctioned.
Nigerian officials began counting votes in some areas in its delayed election on Saturday, after gunfire and explosions started voting day.
The vote, widely seen as too close to call, also was marred by hours-long delays at polling stations across the vast West African country.
Polls closed in many areas, although voting continued in units that opened late.
Preliminary results are expected in about two to four days, according to observers.
More than 72 million Nigerians were eligible to vote in this election as President Muhammadu Buhari seeks a second term in Africa's most populous nation and largest economy.
President Buhari was one of the first in the queue when the nearly 120,000 polling stations began opening at 0700 GMT.
He voted in his hometown of Daura, in northwest Nigeria.
Buhari, 76, of the ruling All Progressives Congress (APC) party was accompanied by his wife, Aisha, and surrounded by a crowd of supporters.
As he emerged from the polling booth, he was asked whether he was confident of winning.
"I will congratulate myself. I'm going to be the winner," he told reporters.
Buhari is seeking a second term of office but is facing a strong challenge from Atiku Abubakar, a former vice-president from the main opposition Peoples Democratic Party (PDP).
Abubakar was due to vote in his home state of Adamawa, in northeast Nigeria.
TRT World spoke to journalist Phil Ihaza in Abuja for more.
Election observers report 'peaceful' vote
Domestic and international observers to the Nigerian presidential elections were present at polling stations in Yola and Abuja.
Domestic observer Jude Okafor said voting in Yola was peaceful.
Also in Yola, voter Alhaji Sulaiman Baba said, "although it's too early to judge but the security, they are here and everybody is behaving responsibly."
In Abuja, Maria Arena, a member of the European Parliament and Chief Observer of the European Union Election Observation, explained the EU's role in observing elections in Nigeria.
"Before dealing with migration, we have to deal with freedom in a country," she said, adding that migration "is the last thing we have to talk about."
Observers said the delay of the election from last week, blamed on logistical challenges, could favour President Buhari and the ruling party, with some Nigerians saying they didn't have the resources to travel to their place of registration a second time.
Troops fight off Boko Haram
One soldier was killed and 20 others were injured in a Boko Haram rocket attack in northeast Nigeria, security sources said on Saturday, just hours before elections began.
A civilian militia source in the Borno state capital, Maiduguri, told AFP "at least 13" blasts were heard throughout the city at about 6:00 am (0500 GMT).
Residents also confirmed hearing the explosions while one of two security sources said: "Boko Haram terrorists attempted to enter the city but were intercepted.
"They resorted to firing RPGs (rocket-propelled grenades) on the city. Attempts have been made to locate the source of the firing."
The second source added that one of the explosions happened at the headquarters of the Nigerian Army 7th Division as troops prepared to go out on operations.
"One soldier was killed and 20 were injured. There were other explosions at Maimalari barracks but there was no casualty," he added.
"Troops are out searching for the location of the firing."
Three of the mortars fell in an open rice field in the Teachers Village camp for people displaced by the conflict. But there were no immediate reports of casualties.
A fighter jet was seen flying over the city in the search for the source of the attacks.
There was no official comment from the military but Borno police commissioner Damian Chukwu denied any attack. There was "no threat to public peace and order", he said.
"The gunfire was not targeted at members of the public but was for security purpose," he added.
Fears of a major Boko Haram attack have been growing in the run-up to elections, which the militants have previously vowed to disrupt.
Maiduguri is the birthplace of Boko Haram and has been repeatedly attacked during their nearly 10-year insurgency that has devastated the remote region.
Presidential and parliamentary elections
Voting began from 0700 GMT for the presidential and parliamentary elections across the country.
Security sources meanwhile reported clashes between the military and suspected Boko Haram fighters in Auno, on the border of Borno state with neighbouring Yobe.
An attack in the town of Geidam, north of the Yobe state capital Damaturu, also forced residents to flee, they added.
Military spokesman Colonel Musa Sagir confirmed the attack on Geidam, the hometown of Yobe's governor, saying it happened at 6:30 am [local time].
The statement said the attack was repulsed and there were no casualties, adding that the situation is now calm in Geidam, allowing people to vote.
There were also blasts in Maiduguri, the capital of Borno state, shortly before polls opened that police said they triggered for "security calculations" in a show of force to deter the militants.
The early morning explosions in Maiduguri come after a Boko Haram attack late on Friday on Zabarmari village, 10 km outside the city.
Boko Haram attacks
Boko Haram's insurgency in northeast Nigeria has killed more than 27,000 people and left 1.8 million homeless, creating a humanitarian crisis.
But the government and military have repeatedly said the militants are weakened to the point of defeat, despite persistent hit-and-run raids and suicide bomb attacks.
Recent months have seen an increase in attacks against troops, blamed on or claimed by Boko Haram's Daesh West Africa Province (ISWAP) faction.
The Daesh-backed group is known to operate in northern Yobe state and around the border with Borno state.