Tanzanians voted on Wednesday amid claims of irregularities by opposition parties and violence in some parts of the country.
By the time polling stations closed at 4pm local time, the main opposition candidate Tundu Lissu and several other supporters were calling for mass action if the voting code is flawed.
The ruling CCM presidential candidate John Magufuli cast his vote in Dodoma, the commercial capital of Tanzania, early in the morning, before congratulating electoral officials for doing a superb job.
"Congratulations to the returning officers for the preparations. I congratulate Tanzanians for this important day.
"My call is for them to turnout in large numbers and vote for the candidates of their choice. We also need to maintain our peace and I always say there is life after the elections."
Magufuli did not take questions from journalists during the media briefing. But his main opponent Tundu Lissu of Chadema party cried foul of "rigging". In the afternoon, he claimed polling agents from his party and allies had been restricted in several stations across the country.
"Voting reports indicate widespread irregularities in the form of preventing our polling agents from accessing polling stations," Lissu wrote on his Twitter age and also cited a video clip circulating on the platform of citizens who had arrested with marked ballot papers.
"If this continues, mass democratic action will be the only option to protect the integrity of the election."
The National Electoral Commission which manages Tanzanian general election did not confirm if the ballot papers were authentic material for the election day.
More than 29 million people had registered to vote as stations opened from 7am, and were expected to close at 4pm. And although the NEC did not announce the turnout, long queues were seen in most parts of the country, especially on the Zanzibar archipelago.
Turnout during the morning hours during Tanzania's general election hit high in a largely peaceful exercise spread across different polling stations in Ilala constituency.
Chama Cha Mapinduzi's (CCM) parliamentary candidate for Ilala in Dar es Salaam Mussa Hassan 'Zungu' said the current environment is conducive for peaceful election in his constituency.
He said soon after casting his vote at the Mission Quarters - Mchikichini polling station where he also surveyed several other polling stations and saw that there were no security concerns or any notable challenges.
"There was also a huge voter's turnout especially in the morning. Businesses around this area opened late because people went to vote," Mr Zungu told The Citizen.
Chama Cha Ukombozi wa Umma (Chauma) party's presidential candidate Hashim Rungwe, however, said that the number of voters earlier in the day was less than expected. Mr Rungwe cast his vote at 10.30 am, where he argued he had seen only queues of women.
Mr Rungwe, who made headlines after his party promised to distribute rice once elected, advised voters to return home soon after casting their votes stations to avoid chaos and exercise a peaceful election.
"We planned that every polling station should have at least 400 to 450 registered and eligible voters, but my advice is that there should be 200 voters at a time in every polling station to avoid congestion," Rungwe said.
As voting kicked off, CUF parliamentary candidate Salum Barwani claimed agents had been blocked from entering the venue.
Speaking to Mwananchi Digital, Mr Barwani said some agents in several polling stations were denied access at beginning of the exercise.
"The returning officer who doubles as the Lindi Town Executive Director delayed sending copies of names of agents representing political parties to their respective stations, therefore creating inconveniences that saw some agents being denied access," he said.
"I have communicated with the returning officer who has assured me that immediate measures are being taken to streamline the process.
NEC did not immediately respond to the claim but Chadema, CUF, NCCR and ACT agents in Ngamiani South, Zanzibar were taken into police custody after they reportedly blocked voters to go into the polling station because they had been denied access.
In Dar es Salaam, opposition party Chadema claimed that its parliamentary candidate for Kawe in Dar es Salaam, Ms Halima Mdee was under police custody, just hours after the polling started.
Ms Mdee, who doubles as chairperson for the opposition party's women's wing known by its Kiswahili acronym as Bawacha, has been the legislator for Kawe for two five-year terms consecutively.
Mdee was later released from Police custody. But Kinondoni Regional Police Commander, Edward Bukombe said she had been questioned over an altercation she had had over voting without presence of party agents.
Reporting by Alawi Masare, Louis Kolumbia, Pamela Chilongola, Ephraim Bahemu and Josephine Christopher