But AU observers had noted of concerns raised by opposition leader Raila Odinga, who claimed the IEBC systems were "hacked", allegedly by incumbent President Uhuru Kenyatta's Jubilee party and that the results so far were a "fraud".
Mr Odinga has claimed hackers could have used the identity of murdered election official Chris Msando to "create errors" in the country's electoral database.
Despite allegations of vote-tampering, that last occasion was a largely peaceful affair, unlike the vote a decade ago which descended into ethnic violence across the country, killing over a thousand people.
Instead, the election board was displaying a running tally on its website that showed President Uhuru Kenyatta leading with 55 percent of the vote to Odinga's 44 percent after almost three-quarters of polling stations had reported results.
A similar situation with a systems failure in the 2013 election led to Odinga's legal challenge at the time, though Kenya's Supreme Court ruled in favor of Kenyatta by validating the results.
Many parts of Kenya, East Africa's commercial hub, remained calm, but the violence stirred memories of the unrest that followed the 2007 vote in which more than 1,000 people were killed.
The election is seen as too close to call as both candidates held intense campaigns prior to today's voting.
Kenya's election commission said that it hoped to have all results centralised by midday on Friday and would announce a victor soon after.
Odinga said that according to.
One person was killed when a machete-wielding gang attacked a tallying centre in the coastal Tana River county, and police shot dead two attackers, a witness said.
Odinga appealed for calm at the press conference, but added: "I don't control the people".
At their Gatundu home, President Uhuru Kenyatta prepared to cast his ballot at the Mutomo Primary School.
Under a power-sharing deal brokered by former United Nations secretary-general Kofi Annan, Mr Odinga served as prime minister from 2008 to 2013.
Kenya's Independent Electoral and Boundaries Commission officials make a sweep of electoral material 7 August 2017 at a holding centre in Kagio.
However, Kenya's electoral commission has denied the claims that its IT system was hacked in order to manipulate the election results.