Angry opposition supporters in Nigeria's Muslim north set fire to homes bearing ruling party banners on Monday and heavy gunfire rang out in several towns as election officials released results showing the Christian incumbent had gained an insurmountable lead.

Results were still pending in four states from Saturday's election but tallies released live on national television indicated President Goodluck Jonathan had a commanding lead of more than 11 million votes and only about six million were left to be announced. The Muslim north had largely voted for the former military ruler, Muhammadu Buhari.

Witnesses said youths in the northern city of Kano were setting fires to homes that bore Mr. Jonathan party banners. Heavy gunfire also could be heard. An Associated Press reporter there saw hundreds of youths carrying wooden planks in the street, shouting “Only Buhari” in the local Hausa language.

Election officials said they would finish releasing election results later on Monday regardless of the ongoing violence.

Nigeria's elections have long been marred by violence and rigging. But voting in the Saturday presidential election had been largely peaceful apart from a hotel blast that wounded eight people and the fatal shooting of a police officer at a polling station.

Nigeria, a nation of 150 million, is divided between the Christian-dominated south and the Muslim north. A dozen states across Nigeria's north have Islamic Shariah law in place, though the area remains under the control of secular state governments.

Thousands have been killed in Muslim-Christian violence in the past decade.Mr. Jonathan, who became President after his Muslim predecessor died in office, last year, has long been considered the front-runner. However, the country's Muslim north remains cold to Mr. Jonathan.

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