The United States is urging Kenyan candidates not to use violence if they dispute any results of Tuesday's election.
A State Department statement on Thursday urged Kenyans to patiently await the election commission's announcement of official results. It is not yet clear when that will happen.
Supporters of opposition leader Raila Odinga said an unofficial tally shows that he won. That claim conflicts with a provisional official result that has incumbent President Uhuru Kenyatta in the lead.
International observers say they have not noted any signs of interference with the vote.
A Kenyan official says violence has broken out in the county of Garissa, where opposition supporters are demonstrating against the announcement of a ruling party candidate as the winner of a gubernatorial race.
North Eastern Regional coordinator Mohamud Saleh says police are trying to restore calm after part of the town's market was burnt by arsonists.
