Nigerian President Goodluck Jonathan has taken a wide lead in presidential election results, as vote-counting continues in Africa's most populous nation.
The website of Nigeria's Independent National Electoral Commission shows Jonathan winning 16 of the 19 states for which results are posted. Main opponent Muhammadu Buhari has made a strong showing in his northern, mainly Muslim strongholds.
To win and avoid a run-off, a candidate needs a simple majority and at least a quarter of the vote in 24 of the nation's 36 states.
President Jonathan - a Christian from the oil-producing Niger Delta - was the clear front-runner among several candidates going into the race. Buhari, a former military ruler, is from the Muslim north. He has lost two previous runs for president.
Election-related violence flared late Saturday after observers said voting mostly proceeded calmly, with few instances of cheating.
Police said a bomb detonated late Saturday at a hotel in northern Nigeria, wounding eight people. Details of the explosion remain unclear. The bomb went off in Kaduna, the home state of Vice President Namadi Sambo.
Other incidents of violence were reported in the north, where police say at least one official's house was burned and several riots broke out.
Security was tight at polling stations across the West African nation, which has a history of rigged voting and election violence. There were two explosions in the northeastern city of Maiduguri early Saturday.
Observers say voters turned out in large numbers for the election.
President Jonathan has promised to improve the country's economy, health and education. He assumed the presidency last year following the death of his predecessor, Umaru Yar'Adua.
Mr. Buhari said he would not contest the results of the election, should he lose. If elected, he vowed to clean up corruption and invest in Nigeria's infrastructure.