LAGOS (AFP) - Nigeria's ruling party lost key parliament seats in the first of three crucial elections this month, results showed Sunday, after millions cast ballots despite deadly bomb blasts and delays. Violence cast a shadow over a bid by Africa's most populous nation to hold a credible vote after a series of violent and deeply flawed elections, but officials and activists said the polls were a marked improvement. The twice-postponed parliamentary polls on Saturday are to be followed by presidential elections on Saturday and governorship and state assembly ballots on April 26. Results were being announced in each voting district Sunday, though some areas of the country's north voted until 2:00 am because of high turnout, possibly delaying announcements there, residents said. Early indications gave the opposition Action Congress of Nigeria a strong showing in the country's southwest, where the economic capital Lagos is located. The Congress for Progressive Change opposition, whose presidential candidate M Buhari, an ex-military ruler, is seen as the main challenger to incumbent Goodluck Jonathan, appeared to make inroads in the north. A spokesman for the speaker of the house of representatives, Dimeji Bankole of the ruling PDP, confirmed he had lost and said he did not intend to contest the defeat. There were also reports that Iyabo Obasanjo-Bello, daughter of ex-president Olusegun Obasanjo, had lost her senate seat. National assembly members have in the past frequently changed parties, making it unclear what effect the PDP's losses would have, especially if Jonathan wins the presidential election. But there was a sense that Nigeria had entered new territory, with efforts to conduct a fair vote seen as providing a greater opening for opposition parties, and that old patterns may not necessarily hold. Observers cautioned that they had not yet been able to gain a full picture of Saturday's vote, but said initial signs were positive. The president of the National Democratic Institute, which has more than 60 observers in Nigeria, said the election appeared to have been a change from the country's heavily criticised polls since a return to civilian rule in 1999. "It was a real election, and it was a real vote," said Kenneth Wollack, who however expressed concern over the violence and the upcoming two elections, when turnout and tensions are expected to be greater. A major effort has been undertaken to organise credible polls, with the appointment of a respected academic to head the electoral commission, who ordered a series of reforms. The previous voter list - which was littered with false entries, including Mike Tyson and Nelson Mandela - was thrown out and replaced with a new one, compiled by taking electronic prints from each finger of every voter. Safeguards meant to stop election-day rigging and ballot-box snatching - major problems in Nigeria - were also in place. There was clear enthusiasm across the country to cast ballots despite a bomb attack on an electoral office on Friday night that killed 13 people and wounded dozens. Two other explosions occurred in the northeastern city of Maiduguri on Saturday - one at a polling place and another at a vote collating centre. Authorities had not officially confirmed any deaths, but sources said a number of people had been killed. There was also sporadic violence in other areas, including in the oil-producing Niger Delta, notorious for election rigging and intimidation during past polls. Speaking on Saturday evening, electoral commission chief Attahiru Jega said the day appeared to have gone generally well. "There are also very few cases of ballot-box snatching - evidently by politicians still living in the past," he told journalists. "They still think that if they steal ballot boxes and steal ballot papers and steal result sheets, that they will still be able to declare fraudulent results."