The harsh warning came as the announcement of results in the hard-fought race began to trickle in.
Nigerians celebrated a relatively peaceful election day, but worried about fraud and possible violence.
Boko Haram insurgents pose a threat, as do voters who could erupt into protest if their candidate loses.
Presidential candidates have pledged to defeat the extremist group but many worry about its reach.
Nigeria is Africa’s most populous and oil-rich country, and the elections may affect not just this country but others in West Africa.
The reports came with elections just days away and the government claiming success in the multinational campaign against the militant group.
After losing 29 relatives, Josephine Dolley took in six orphans and is determined to provide for them despite Liberia’s economic crisis.
The epidemic might be fading in West Africa, but U.S.-funded scientists in Congo fear a new one could be lurking in the remote rain forest among jungle animals.
Adan Garaar, a senior leader in the militant group, may have been killed in the strike in Somalia, officials say.
After years with extremists, they had “a blankness in their eyes” and spoke Arabic.