State elections in Nigeria have been marred by late opening of polling stations, missing ballot papers and in some areas violence and intimidation.
It took a long time for many people to complete the voting process
Voting had been extended because of the late opening but it has now ended and ballots are being counted.
The polls are a key test ahead of next weekend's presidential elections.
President Olusegun Obasanjo said he thought polling had gone relatively well but the opposition said there were widespread irregularities and fraud.
The outcome of Saturday's election for governors and state legislatures is as important to many Nigerians as the presidential poll.
State governors can be extremely powerful, controlling budgets of around $1bn, especially in oil-rich states.
The poll was being seen as an important indicator of how free and fair the presidential polls will be.
Nigerians lined up in the sun for hours to cast their ballots, with many having to put up with the late arrival of election officials, inadequate voting materials, and in some cases, intimidation by youths supporting one party or another.
President Obasanjo had said that fraud or violence would not be tolerated.
But in Port Harcourt - the largest city in the oil producing Niger Delta - the BBC's Alex Last said there was genuine fear of violence and vote rigging.
Our correspondent was at one polling station that had only been open for a few minutes when a gang of young men on motorcycles stormed it and made off with the ballot papers and ballot box.
Early on Saturday, suspected militants torched three police stations, killing seven policemen.
In the commercial capital, Lagos, an opposition stronghold, the streets were abnormally quiet and the military was out in full force manning checkpoints at key road junctions.
Many polling stations in different parts of the country opened several hours late.
The BBC News website's Senan Murray was at a polling station in the Rukuba area of Jos in central Nigeria and saw eager people queuing to vote from early on Saturday.
But electoral officers only turned up just before midday to open the polling station.
Voter Yakubu Ropshak, 27, said: "We are waiting and we are not going anywhere until we vote."
In some areas of Rivers State and Delta, voting had not begun by mid-afternoon, Reuters reported.
Electoral chief Maurice Iwo assured Nigerians that "people who are already at the polling stations will be allowed to vote, no matter how late".
Many busy centres were staying opening into the evening to allow people to cast their ballots.
There were pockets of violence in some other parts of the country where election materials were destroyed and electoral officers attacked.
Mr Obasanjo said "highly-placed" people were encouraging violence