Kenyans began voting on Tuesday in general elections, with a tight, bad-tempered race between President Uhuru Kenyatta and his longtime rival Raila Odinga sparking fears of violence.
Polls opened with varying delays after the official start at 6am (0300 GMT) in strongholds of both candidates around the country, according to AFP reporters.
A 15 minute delay led to shouts of anger in Nairobi's largest slum Kibera, an opposition stronghold, where thousands waited outside a primary school to cast their ballots, many draped in a red Maasai blanket to ward off the chilly morning air.
However voting soon got underway.
"We must choose wise leaders, because the previous ones have kept all the wealth for them, they did nothing against corruption," said 20-year-old Benson Kamano, who is unemployed.
"I am all for Odinga, he will change things."
Tensions have soared in east Africa's richest economy as the campaign ended with the murder of a top election official, and Odinga has repeated claims the vote will be rigged.
"If the election is fair, there will be no violence," said Kamano.
At Moi Avenue Primary School, the largest polling station in the city, voter Calvin Otieno, 27, joined the queue shortly after midnight.
"Everyone has a right to vote and we should all be ready to accept the results. There is no need to fight because of elections. We are all Kenyans irrespective of tribe. If we fight, will any of the candidates come to bring us food in our houses?" he said.
In Kenyatta's home town Gatundu, north of Nairobi, a voter who identified herself only as Gathoni also arrived early to "vote for my favourite president", who will himself cast his ballot at the polling station later in the morning.
Kenyans will vote in six different elections, choosing governors, lawmakers, senators, county officials and women's representatives in local races also rife with tension.
Each ballot paper was a different colour, with a corresponding ballot box.
Security was tight at the polling station and around the city, with at least 150,000 officers deployed. Odinga has warned this may intimidate voters.
On the eve of the vote US President Barack Obama led international calls for peace in the country seen as a bastion of stability in east Africa, and a key partner in the fight against the Al-Qaeda linked Shabaab group in Somalia.
"I urge Kenyan leaders to reject violence and incitement; respect the will of the people," Obama said in a statement.