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Sunday Alamba, Associated Press
Nigerian people look for their names before they register to vote in Lagos, Nigeria, Saturday April 11, 2015. Nigerians are voting for state governors and assemblies in elections where the opposition hopes to make gains following its stunning victory that unseated President Goodluck Jonathan two weeks ago.

LAGOS, Nigeria — Nigeria's opposition is winning key states from the party of defeated President Goodluck Jonathan, with results still coming in Monday from weekend elections marred by killings, low turnouts and the snatching of ballot boxes.

The party of President-elect Muhammadu Buhari won a tight contest for Lagos, Nigeria's financial hub. And it won landslides in northern Kaduna, Sokoto and Katsina states, which Jonathan's party had governed since decades of military rule ended in 1999.

Results were still coming in from weekend voting for governors in 29 of the 36 states.

Opposition candidates are contesting the victory announced for Jonathan's party in oil-rich southern Rivers state, where nine people were killed, a polling station and home of a Jonathan party official were set ablaze, and several electoral workers were kidnapped.

Politicking has been violent in Rivers since outgoing Gov. Rotimi Amaechi defected to the opposition last year.

There were no immediate reports of violence involving the insurgents, who killed about 40 people including three young electoral workers during the presidential vote.

Turnout at the weekend was low

"People are afraid of violence, so they stayed at home," voter Abdullahi Tahiru told The Associated Press.

The Independent National Electoral Council canceled the election in southern Imo state, where ballot materials did not reach several polling stations, and in Taraba, where ballot boxes were snatched and thugs attacked the homes of two officials of Jonathan's party.

Nigerians also voted for national legislators in the March 28 presidential elections, with results from individual states showing Buhari's party has won control of both houses.