Election Officials in Tanzania say, the country has recorded high turnout in the general elections.
The election is to end the governing party's 54-year grip on power.
Accroding to officials, voting was extended in some areas to allow those still in queues to cast their ballots in what has been described as Tanzania most competitive elections,
Opinion polls have put the governing Chama Cha Mapinduzi (CCM) party ahead, but the result is expected to be close.
Four opposition groups are backing a former prime minister.
The BBC reports from the main city ,Dar es Salaam that usually busy streets and markets are deserted, and large queues have formed at polling stations as people wait patiently to cast their ballots.
President Jakaya Kikwete, who is standing down after two terms, has called for peace ahead of the election, adding that "anyone who tries to cause trouble will be dealt with".
CCM was formed in 1977 from a merger of two post-colonial parties and has effectively been in power since independence in 1961.It has fielded Works Minister John Magufuli, 55, as its presidential candidate.
President Jakaya Kikwete, is being challenged by Edward Lowassa, 62, who quit CCM after he failed to win its presidential nomination. He is contesting the poll under the banner of the Ukawa coalition.