Kenyans nervously eyed results trickling in Tuesday from the presidential election, the first since disputed polls five years ago triggered a wave of bloodletting, with deputy prime minister Uhuru Kenyatta taking an early lead.
Kenyatta, who faces a trial for crimes against humanity over the violence that killed more than 1,100 people and forced over 600,000 to flee their homes, edged ahead in partial results over rival Prime Minister Raila Odinga, who says he was robbed of victory in 2007.
Millions of Kenyans turned out peacefully on Monday for the elections, seen as key to stability in the regional powerhouse.
Voters stood for hours in snaking lines several hundred metres (yards) long and several people thick outside polling stations to take part in one of the most complex elections Kenya has ever held.
Partial results from some 37 percent of the almost 32,000 polling stations -- with over 4.4 million valid ballots counted from the 14.3 million registered voters -- had been sent to the central tallying centre in the capital Nairobi.
Of those counted at 12:15 pm (0915 GMT), Kenyatta had won almost 2.43 million or 54 percent of valid votes cast against Odinga with 1.82 million or 40 percent, but with the majority of votes yet to be tallied, Kenyatta's lead could still be easily overturned.
However, more than 277,000 rejected ballots made up a staggering five precent of votes cast.
"This election is a turning point, and its outcome will determine whether the country will proceed as a civilised state," the Daily Nation newspaper said, adding that all Kenyans must "be ready to accept the election results."
Hours before polling stations opened, bloody clashes erupted on the Indian Ocean coast in which six policemen and six attackers were killed, as well as several bombs that wounded one person in Mandera, a northeastern town on the border with war-torn Somalia.
Police chief David Kimaiyo blamed the coastal attacks on suspected members of the secessionist Mombasa Republican Council (MRC), and said that 400 officers had been sent to beef up security in the popular tourist region.
But while few other incidents were reported, there were complaints across the country at the widespread failure of electronic biometric voting registration (BVR) kits introduced to frustrate potential rigging.
The BVR failure meant stations used paper records and manual registration.
Ahmed Issack Hassan, the head of the Independent Electoral and Boundaries Commission (IEBC), told reporters the body was investigating complaints of voting irregularities from political parties.
"I want to assure the candidates and political parties, please don't jump to conclusions: your job is to contest the election, our job is to organise them," Hassan said, adding that he did not expect full preliminary presidential results until at least Wednesday.
-- Patience urged as Kenyans wait --
In the western town of Kisumu -- heartland of Odinga and scene of bitter clashes in 2007 when his supporters grew angry at what they saw as rigged results -- grim-faced people watched the partial results being broadcast on television.
"There is a lot of tension, people are not happy with how things are going," said Nicholas Ochieng, 24.
In the port city of Mombasa, court clerk Ken Malenya drank strong coffee after staying up all night. "I didn't sleep, I want to know who our president will be, I have to know," he said.
To win, a candidate must take more than 50 percent of votes -- as well as winning at least 25 percent of votes in more than half of all counties -- to avoid a second round runoff, due within a month after final results.
Running third, deputy prime Minister Musalia Mudavadi had taken two percent of votes, while none of the other five candidates had taken more than one percent.
The results of the 2007 poll which President Mwai Kibaki won against Odinga sparked a wave of protests, notably because of the lack of transparency in the way the tallying was done.
Odinga and his rival Kenyatta -- one of Kenya's richest and most powerful men -- have publicly vowed there will be no repeat of the 2007-08 bloodshed.
But crimes against humanity trials later this year at The Hague-based International Criminal Court (ICC) for Kenyatta and running mate William Ruto have raised the stakes: should they win the vote, the president and vice-president could be absent for years.
Kenyatta faces five counts including orchestrating murder, rape, forcible transfer and persecution.
The 2007-2008 violence exposed deep tribal divisions and widespread disenchantment with the political class and shattered Kenya's image as a beacon of regional stability.
More checks were in place for Monday's vote to limit rigging, while a new constitution devolving powers has made the poll less of a winner-takes-all race.
Kenyans cast six ballots on Monday, voting for a new president, parliamentarians, governors, senators, councillors and special women's representatives.