Saturday's polls were seen as a test of the electoral system ahead of next week's presidential vote, which will set up the first-ever transfer of power between two elected leaders in Africa's most populous nation.Protests banned
Security had been tight in preparation for the results with soldiers being deployed on the streets of many Nigerian cities.
Police banned any form of gathering in support or against the results amid fears of serious unrest in key states such as Lagos.
"There should be no form of procession. No form of demonstration will be tolerated at this stage, at least in the next 48 hours," Ehindero said.
In the northern state of Bauchi, opposition supporters barricaded the main road to offices of the Independent National Electoral Commission and started fires on the streets.
"We are trying to protect our votes. We know that Mallam [the opposition candidate] has won the election. We are here because we don't want the results to be tampered with," a protester, who gave his name as Baba Ahmed, said.
In the southern oil producing state of Delta, where the PDP was announced the winner, men armed with cutlasses and guns burned down houses and blocked roads in the city of Warri while hundreds of women and children fled on the back of motorcycles.
"They are blocking everyone to show their anger. They are burning buildings and I heard sporadic gunfire," a taxi driver in Warri said. Irregularities alleged
Saturday's polling was hampered by widespread allegations of ballot-box stuffing and other irregularities. the European Union observer mission reported a number of "worrisome" incidents.
The opposition Action Congress has complained of "massive irregularities and fraud" in the vote.
Voting in some areas was hampered by the the late or non-arrival of voting materials and confusion over voter registration, witnesses said.
Ken Nnamani, the Senate president from the ruling People's Democratic Party said there was almost no voting in his native Enugu in southeastern Nigeria because ballots never arrived or arrived very late.
"The exercise was an abysmal failure. If they call a result in Enugu it will be based on manipulation. I'm concerned about the legitimacy of the emerging government," he said.
Youths protesting the absence of ballots in the southern Anambra and Delta states set fire to three INEC offices, while an election officer was stripped naked and abducted in the eastern Ebonyi state.
newspaper said that 52 people had died across the country as voters chose state parliamentarians and governors.