LAGOS, Nigeria -- Fighting between tribal and political rivals disrupted legislative elections in Nigeria's oil-producing south for a second day Sunday. At least two dozen people were killed in the voting and hundreds forced to flee their homes, witnesses and election monitors said.
The vote for 469 seats is a key gauge of civil tensions a week ahead of presidential elections and an important test for democracy in Africa's most populous nation. Military coups have scuttled Nigeria's previous attempts to hold democratic, civilian-run elections.
The voting began on Saturday but was extended to Sunday in several areas where the balloting was marred.
The oil-rich region has been the scene of numerous clashes in recent weeks between Ijaw militants and government troops over voting districts the Ijaws say favor their ethnic rivals, the Itsekiris.
More than 100 people have been killed in the violence, which has shut down 40 percent of the country's oil production. Nigeria is the fifth largest supplier of U.S. oil imports.
On Sunday, sustained automatic weapons fire delayed a second attempt to hold a vote in the oil port of Warri.
Witnesses said navy soldiers and Ijaw fighters were shooting at each other and spoke of between five and 10 people killed. Grace Akpete, a market vendor who fled the fighting, said she saw five bodies floating in the water.
The shooting died down after half an hour. By late afternoon, three elections stations opened, but most remained closed.
"I can't understand why one tribe can hold everyone else to ransom," said Johnson Atake, an Itsekiri waiting to vote Sunday in the port city.
Elsewhere in the Niger Delta, clashes between ruling party and opposition supporters killed 10 people in the town of Nembe, sent hundreds fleeing and left dozens of homes burned, human rights official Azibaola Roberts said, citing witnesses.
Five people were killed Saturday in an ambush on an opposition politician in eastern Enugu state. Gangs of "government thugs" traveling in state vehicles stole ballot boxes at gunpoint, said Ifeanyi Enwerem, director of the Justice, Development and Peace Center. The center has deployed thousands of observers to monitor the voting.
There were also reports of deadly violence in the southeastern city of Onitsha, the southern city of Benin and the eastern city of Port Harcourt.
Still, election commission chairman Abel Guobadia said the voting Saturday went well overall.
In early results from Nigeria's electoral commission, six ruling party incumbents in the northern Kano state -- including House Speaker Ghali Na'Abba -- were upset by rivals. Some opposition members from the southwestern Ondo and Osun states were, in turn, unseated.
Officials have indicated a high turnout across the country of 126 million people. Sixty-one million voters were registered for the ballot, which featured 3,000 candidates.
The vote preceded a presidential election scheduled for April 19. President Olusegun Obasanjo -- a former military ruler turned civilian leader -- is running against 19 opposition candidates, including three former army generals.
The legislative elections are the first since Obasanjo was elected in 1999, ending 15 years of brutal military rule.
More than 10,000 people in Nigeria have been killed in political, ethnic and religious violence since then.