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.
US strikes Iranian launchers on Larak Island
US forces carried out strikes on two Iranian launchers on Larak Island on Sunday, marking the first known American strikes on Iran since late July.
Jordan intercepts eight missiles in airpace
Jordan's air defence systems intercepted eight missiles that entered the country's airspace early on Monday, according to the Jordanian Armed Forces.
At least eight die, 18 missing after ferry capsizes off North Cyprus
At least eight people died and 18 were missing after a ferry carrying around 270 passengers and crew capsized off north Cyprus on Sunday, leaving survivors clinging to its overturned hull.
Rescuers battle floods and debris as Himalayan disaster death toll nears 800
Rescuers in Nepal and China raced on Sunday to find thousands of people missing after a glacier collapse unleashed a catastrophic mudslide across the Himalayas, as they faced challenging weather conditions and rising water levels.
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