Citizens are going to the polls today after a last-minute postponement earlier this week.
The main challenger to reigning president Muhammadu Buhari is former Vice-President Atiku Abubakar.
It is not known exactly when the final results will be announced.
Experts say a winner could be declared as late as Tuesday.
Nigeria is Africa's most populated country.
France's top court blocks social media ban for under-15s
France's top court on Friday blocked a bill banning social media access for under-15s, saying it infringed upon freedom of expression and delivering a setback for President Emmanuel Macron, who asked his government to rewrite the legislation.
Japan's record rains strand thousands at Narita airport; kill eight
Record rainfall in Japan stranded thousands of travellers at Tokyo's Narita airport on Friday, bringing floods to the surrounding area that disrupted transport, knocked out power to 20,000 homes and killed eight.
Tunnel collapses at Indian hydropower project, killing at least 7
A tunnel under construction at a hydropower project in India's northern hill state of Uttarakhand collapsed overnight, leaving at least seven workers dead, officials said on Friday.
Air India A320 briefly lost key flight controls, Airbus analysis shows
An Air India Airbus dropped about 300 feet this month, injuring 24 people on board, after the aircraft registered a loss of hydraulic pressure that briefly left key flight controls unresponsive, according to a preliminary Airbus analysis reviewed by Reuters.
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