Kenyan officials say the re-run of the country's presidential election will be postponed in four counties after three people died in violence.

Police fired gunshots and tear gas in clashes with opposition supporters as voting got under way.

In some parts of the country, protesters barricaded the entrances to polling stations and hurled rocks at security forces.

Image: Residents react as tear gas fills a street in Kibera in Nairobi

Electoral commission chief Wafula Chebukati said that in the western counties of Homa Bay, Kisumu, Migori and Siaya, repeat elections would be held on Saturday due to "security-related" challenges.

One man died after being shot in the head in Nairobi's Mathare slum, a hospital administrator told AFP, while a second death was confirmed in Homa Bay in western Kenya.


Earlier, official sources told the news agency a 19-year-old was shot dead in Kisumu, Kenya's third biggest city and an opposition stronghold, where live rounds and water cannon were also fired.

Image: Kenya's President Uhuru Kenyatta casts his ballot

Police also used tear gas to disperse angry mobs in Kibera, another slum in the capital Nairobi.

August's poll was annulled by the Supreme Court after it found illegalities and irregularities in the election process.

President Uhuru Kenyatta has urged Kenyans to vote in the fresh election, pledging the deployment of security forces nationwide to ensure order.

:: Opposition leader plunges Kenya into a political crisis

Image: Kenyan opposition leader Raila Odinga waves to supporters

But opposition leader Raila Odinga called for a boycott, announcing a "resistance movement" and the establishment of a "people's assembly" as a parallel government.

His call appears to have resonated with voters in some areas, with local media anticipating a lower turnout this time around, even by supporters of Mr Kenyetta, who is seeking a second term.

Some polling stations in opposition strongholds did not open on Thursday, while voting in Mr Kenyatta's hometown of Gatundu and other areas was marred by heavy rains and power cuts.

Image: There were no queues at this polling station in the capital Nairobi

Supporters of Mr Odinga, leader of the National Super Alliance (Nasa), blocked roads leading to some polling stations in Kisumu to prevent residents from voting.

Officials cited fear of attacks for the failure to deliver equipment to some polling stations in the region which remained locked and chained.

"So far, we have not deployed any material, and we have not deployed election officials. The reason is security," said returning officer John Ngutai.

Image: Opposition supporters clash with police in Nairobi as the second poll begins - the first in August was annulled due to irregularities Image: Tear gas has been fired at opposition supporters in the Kibera area of the capital Image: There have also been clashes in Kisumu Image: Unopened, undelivered ballot boxes at a school in Kisumu illustrate the chaos surrounding the vote Image: An election official uses an electronic device to check a voter's identity at a polling station in the capital Image: A member of the Maasai and Kikuyu tribe votes at a school in Masailand Image: Voters queue to cast their ballots at a primary school in Mathare, Nairobi Image: Kenyan opposition leader Raila Odinga Image: Votes are cast at a polling station in Gatundu, the incumbent president's hometown Image: There are no queues at this polling station in the capital Nairobi - with many boycotting the re-run Image: An anti-riot police officer near tyres set alight by opposition supporters in Kisumu Image: Kenyan President Uhuru Kenyatta speaks during a political rally in Nairobi /

Waiting to cast his vote in Mathare, another of the capital's slums, taxi driver David Njeru said: "It is my duty to vote.

"Last time the queue was all around the block and I waited six hours to vote, this time the people are few."

The ongoing dispute has bitterly divided the east African country and plunged it into its worst political crisis since 1,100 people were killed in politically-driven ethnic violence after an election in 2007.