Boko Haram extremists have killed 39 people, including a legislator, in north-eastern Nigeria, disrupting the country's presidential election, officials said.
All the attacks took place in the north east where the military announced it had cleared the Islamic extremists from all major centres.
Residents of the town of Miringa said Boko Haram militants torched people's homes and then shot them as they tried to escape. Twenty five people reportedly died.
Witnesses and officials said another 14 people, including Gombe state legislator Umaru Ali, died later today in attacks on the towns of Biri and Dukku.
Nigeria have extended the voting period for their current elections until Sunday after reported technical issues at polling stations across the country.
Information Commissioner Chris Yimoga told journalists: "In polling units where accreditation was suspended to the following day, in accordance with the existing guidelines, arrangements will be made for voters to vote tomorrow."
State police commissioner Danladi Marcus has told Reuters by telephone that Islamist Boko Haram insurgents launched two deadly attacks on voters in northeast Nigeria on Saturday. The police and a security source said six people in an election in which insecurity is a major issue.
One attack was in Ngalda, Yobe state.
The other was in an ethnic Fulani village called Woru in Gombe state, a security source said.
In both attacks gunmen opened fire on voters as they trekked to their polling stations, killing three in each.
A car bomb has exploded at a polling station as people gathered to vote in the Presidential election in Nigeria's south-central Enugu state.
State Police Commissioner Dan Bature said an anti-bomb squad detonated two other cars filled with improvised explosive devises at the scene at a primary school.
There has been no claim of responsibility.
The explosions occurred far from north-eastern Nigeria, the centre of Boko Haram's Islamic uprising.
Pre-election violence has prompted election frontrunners President Goodluck Jonathan and former military dictator Muhammadu Buhari to sign a 'peace accord' on Thursday.
President Goodluck Jonathan is seeking a second four-year term as leader of Africa`s most populous nation against a strong challenge from the main opposition candidate Muhammadu Buhari.
The vote has been seen as a referendum on Jonathans record over the past four years, with an escalation in the Boko Haram insurgency and the continents top economy hit by the global shock in oil prices.
This is a great day for our son, and we are set to return him to power. He has done well. He deserves a second term.
Buhari, a former military ruler who has a reputation for fighting corruption, also charges that Jonathan has done little to tackle rampant graft in government, particularly in the oil and gas sector.
The election was postponed from February 14 because of military operations against Boko Haram in the northeast, which has since seen a series of claimed successes against the militants.
Polling stations opened in Nigeria its electoral commission said, as voters went to the polls to elect a new president in what is being seen as the closest campaign in the country's history.
"Polling stations have opened. Accreditation has started," Independent National Electoral Commission spokesman Kayode Idowu told AFP, despite reports of delays to the 7am (GMT) start. Reporters said the process had not started at some locations in Kano, Lagos and Abuja because of the late arrival of INEC officials and election materials. Voting proper is due to start at 1:30 pm local time.
United Nations Secretary-General Ban Ki-moon has called on all Nigerians to go to the polls in large numbers as the country decides between incumbent President Goodluck Jonathan and his rival Muhammadu Buhari.
In a statement released by his spokesperson’s office, Mr Ban commended both parties for their commitment to respect the outcome of the elections and called on the candidates and their supporters to resolve disputes that may arise from the electoral process through peaceful means.
“The success of the polls is the responsibility of all Nigerian actors: the electoral authorities, security agencies, political parties, candidates, religious leaders, civil society and voters,” Mr Ban said in the statement.
The Secretary-General’s statement also expressed hope that the elections will be transparent, inclusive, and peaceful.
“The international community has high expectations that Nigeria will provide leadership in setting a high standard for this election,” he added.
The polls in Nigeria's presidential election open at 0700 GMT and close at 1700 GMT.
The Nigerian army said it has captured the strategically significant town of Gwoza from Boko Haram.
Making the announcement on social media, the army said it had killed several members of the group and that a "mop-up" was now underway.
Nigerian media are reporting that more than two hundred of the girls captured in Chibok in April 2014 are being held in the town, in Bornea State.
A 56-year-old woman who was kidnapped by the group in 2014 and held in two locations by the group told the International Centre for Investigative Reporting that she was held along with the girls under very tight security in a house in Gwoza.
The town was first captured by Islamist fighter last year, and was declared the headquarter of the group's Caliphate.
Residents have said Boko Haram militants have kidnapped more than 400 women and children from the northern Nigerian town of Damasak that was freed this month by troops from Niger and Chad.
"They took 506 young women and children (in Damasak). They killed about 50 of them before leaving," a trader called Souleymane Ali told Reuters in the town.
"We don't know if they killed others after leaving, but they took the rest with them."
Troops from Niger and Chad last week found the bodies of at least 70 people in an apparent execution site under a bridge leading out of Damasak, where the streets remain strewn with debris and burnt-out cars after the fighting.
Armed forces from Chad and Niger have teamed up to launch a fresh offensive against Islamist militant group Boko Haram in Nigeria.
Troops entered the country through southeast Niger and attacked militants in Nigeria's Borno State.
We can confirm that Chadian and Nigerian forces launched an offensive this morning from Niger. The offensive is underway.
It comes after Boko Haram pledged allegiance to Islamic State, which has taken over parts of Iraq and Syria.