VOA News. ABUJA, NIGERIA- Millions of Nigerians turned out to choose a new president Saturday, but technical problems with a new computerized anti-fraud system caused delays and long lines and prompted officials to extend voting into Sunday.

It was unclear how widespread the problems were, but the decision to extend the vote, which pits incumbent Goodluck Jonathan against his main rival, Muhammadu Buhari, added more uncertainty to an already tense election campaign.

The vote had already been postponed in February, as officials cited security concerns from the Boko Haram insurgency, which has ravaged the country’s northeast.

Voting Saturday was also marred by an attack by suspected Boko Haram insurgents in the northeastern state of Gombe. Witnesses told VOA that gunmen attacked three villages in the state, killing at least 24 people.

Borno state Governor Kashim Settima said insurgents killed 25 people in the village of Buratai on Friday.

Voting problems

Election officials have touted a new biometric voter card system as insurance against the fraud allegations that have tainted previous elections. But in some places, hand-held card readers machines appeared to malfunction in reading the cards.

Many polling stations opened late because of delays in getting voting materials, and problems with the accreditation process.

Voters at one station in Lagos, Nigeria’s largest city, told VOA they waited in line for several hours while election workers looked for a machine that would work.

“We want to vote so we’ve been here since 8 o’clock. Some people have gone. They’ve gone,” said Dorothy Offia, 35. “We’ve been here since morning.”

Jonathan, who cast his vote in the southern town of Otuoke, needed 30 minutes to go through the process.

At one station, on the outskirts of the capital Abuja, a VOA reporter watched officials struggle with the card-reader machines, trying to verify voter fingerprints. Some staff tried several different fingers for voters, trying them multiple times, and still not succeeding. Officials urged voters to wipe their fingers or wash their hands to try to fix the issue.

In Kano, a city of two million located around 300 miles north of Abuja, a VOA reporter visited multiple polling stations Saturday morning, but found only one that had working card readers. About 100 people lined up at the station, waiting to cast their ballots, as well as a handful of security personnel and agents from the electoral commission.

The Independent National Electoral Commission announced early Saturday evening that because of the technical problems, voting would be extended into Sunday.

“Whereas the process has gone on well in several places, in some others it has encountered some challenges, especially with the use of the card readers,” the commission said in a statement on its Web site. “Consequently, accreditation has been slow in many places and has not commenced at all in some others.”

Despite the delays, however, the vote appeared to be proceeding calmly.

“I think any moment from now the materials will be here,” voter Samuel Eke told VOA in the southern city of Port Harcourt. “You can see the enthusiasm amongst the people. We want to exercise our vote. We have all the hope that materials were sent out to the various units. So maybe we’ll give them some time.”

The electoral commission Web site went offline earlier Saturday, when a hacker group calling itself the Nigerian Cyber Army attacked the site, posting a message warning officials not to rig the polls.

Jonathan and the ruling Peoples Democratic Party are facing a tough challenge from the Buhari and his opposition backers, the All Progressives Congress.

Past elections have been marred by allegations of vote rigging. Violence after the disputed 2011 elections, which also featured Buhari challenging Jonathan, killed some 800 people.

Earlier in the week, both Jonathan and Buhari pledged to respect the outcome of the election as long as it is “free, fair and credible.”

Jonathan, 57, is a Christian from the Niger Delta oil region in the south, while 72-year-old Buhari is a Muslim from the north. Pre-election polls showed the two in a very close race.

Preliminary results may be announced as early as Sunday, though a final certified tally was not expected before Monday at the earliest.

Delayed in February

The vote was postponed in mid-February because of fighting and insecurity in the northeast where the Boko Haram insurgency has raged since 2009. The government’s inability to stop the Islamist extremist group was a major issue during the campaign.

Security across Nigeria has been tightened leading up to the election amid concerns insurgents could attack polling stations.

In recent weeks, a multinational offensive drove Boko Haram from most of the towns it controlled in the northeast. On Friday, the Nigerian military said soldiers took back the town of Gwoza and destroyed the headquarters of Boko Haram’s self-declared caliphate.

U.S. intelligence officials expressed caution about the report, saying that even if the militants had retreated, it does not necessarily mean they are near defeat.

Intelligence officials told VOA that Boko Haram has used strategic retreats in the past only to wait, sometimes for weeks or more, for an opportunity to launch a devastating counter attack.

Chris Stein reported from Kano, Nigeria.