Zambia's electoral commission called on candidates to be patient Friday as election workers tallied general election results in 10 provinces.
Observers reported a massive turnout Thursday at polling stations across the country, including the capital, Lusaka.
Zambia election officials promised they would announce the results within 72 hours after the last citizen voted.
Electoral commission spokesperson Patricia Luhanga said the commission was pleased with the large turnout.
"The numbers we've seen are quite unprecedented," she said. "And for us as a commission, this gives us a sense of pride. Because we look at the total number of registered voters that is slightly above 7 million and we look at the queues that we have experienced on poll day. We have nothing but a sense of pride."
Zambians voted to choose a new president, parliament and local representatives in an election that analysts said was a test for one of Africa's pillars of democracy.
President Edgar Lungu, 64, faced his fiercest competition from a familiar challenger, Hakainde Hichilema, 59, one of 15 opposition candidates.
Analysts predicted a tight race to determine the country's political future, and a second round could result if no candidate receives more than 50% of the ballots cast.
Officials said they would give regular updates to keep the country informed about the tabulation.
But social media tools such as WhatsApp, a crucial form of communication in the provinces, have been curbed. The government has not commented on outages on the internet.
'Unblock the internet'
Opposition presidential candidate Hichilema accused the ruling party on Twitter of orchestrating the social media disruptions. He said he wanted telecom regulators to "unblock the internet so citizens can follow the electoral process and continue with their lives unhindered.”
Clashes between supporters of the governing Patriotic Front (PF) and partisans of the main opposition United Party for National Development (UPND) alliance left two people dead in one constituency in Lusaka earlier this month.
But officials of the African Union Poll Observer Mission said representatives of political parties at the polling stations they visited had no problems and were pleased with how the elections were administered.
Former Sierra Leonean President Ernest Bai Koroma, who led the AU observers, told VOA he was pleased with how Zambians behaved during voting.
Koroma commended the patience and decorum of the large crowds at the polling stations he visited. He also praised the professionalism of the electoral commission staff at the polling stations as well as the police there to maintain the peace.
"Personally, I have been impressed with what I have seen so far," Koroma told VOA. "Even at 6 a.m., you have long queues lined up. It shows a lot of enthusiasm and excitement on the part of the Zambians to exercise their civil responsibility. It's very impressive.”
Before election day, Koroma met with many candidates, including Lungu, Hichilema and others.
"We have cautioned them, even those that have concerns, that ... we will address the concerns," he said. "It is all part of building the democratic process, [and] we will continue to engage."
Some information for this report came from Reuters.