Nigerian flag (Creative Commons)

With nearly 22.5 million votes, Jonathan overtook challenger Muhammadu Buhari, of the Congress for Progressive Change, who won 12.2 million votes.

The votes were cast largely along regional lines with Jonathan, of the ruling People's Democratic Party, taking the south and Buhari taking the north.

"Goodluck E. Jonathan of PDP, having satisfied the requirements of the law and scored the highest number of votes, is hereby declared the winner," declared Attahiru Jega, chairman of Nigeria's Independent National Electoral Commission.

News of Jonathan's reelection sparked violence in northern Nigeria. Opposition supporters rioted, burning buildings and attacking members of the PDP.

Reuter's reports:

Nigeria Red Cross spokesman Seyi Soremekun said that 101 people were injured in the outbreaks, which were participated in by thousands of people throughout the north -- including Kaduna city and Zaria, in Kaduna state, and Kano.

A witness in Kaduna said that a 24-hour curfew was imposed there.

Jonathan spoke out against the violence Monday.

"I enjoin our political and religious leaders in their usual sense of patriotism to call on their followers to eschew all acts of bitterness and violence," said Jonathan. "As I have always stated, nobody's political ambition is worth the blood of any Nigerian."

Nigeria is no stranger to violence, though.

From Bloomberg:

Since Nigeria’s return to civilian government in 1999 after 15 years of military rule, income disparities have widened, fueling ethnic and religious violence. About 54 percent of the population lives on less than $1 a day, about 22 million citizens are illiterate, and maternal mortality is 800 per 100,000 live births, a rate among the highest in the world, according to the United Nations Development Programme.

The results came amid accusations of voter fraud with the Congress for Progressive Change accusing the PDP of intimidating voters and stuffing ballot boxes.

However, Project 2011 Swift Count, a Nigerian observer group, says the allegations are false based on reports from polling places.

"These elections were not without problems -- in particular, isolated incidents of intimidation, violence, and illegal voting. But these incidents did not undermine the overall credibility of the process," said the group.

Watch footage from ITN News below: