STORY: The chairman of the electoral commission Wafula Chebukati said Ruto had won 50.49% of the vote, against his opponent Raila Odinga 48.5%.
The winning candidate must get 50% of votes plus one. Odinga did not attend the announcement.
Kenyan police fired tear gas at protesters in Kisumu after the elections chief declared Ruto the winner.
Several black plumes of smoke rose as people burned piles of tires in Kisumu, a stronghold of veteran politician Raila Odinga, amid shouts of "We need Raila now!" "Chebukati must go!" and "No Raila, no peace!,"