Three people carrying weapons have been arrested in Ugenya, Siaya County, as residents headed to the polls.
Police say they planned on disrupting the by-election.
A panga and stones were found in a car.
Ugenya OCPD Willy Simba said they arrested the three after a tip from the public at around 3am.
Suspects Emmanuel Odhiambo, Hillary Ochieng and Erick Onyango were arraigned in court and released on Sh5,000 bond.
They were charged with preparing to commit fellony.
Voting started smoothly, but with a few delays on kits not working.
Daniel Juma, who is contesting on a Grand Dream Development Party ticket, and Brian Omondi of Third Way Alliance, are, however, registered in Nairobi.
The two will face David Ochieng' and ODM's Christopher Karan.
Violence cases were reported in North Ugenya where supporters attacked each other.
Out of the five involved, two escaped as the rest were detained at Ukwala police station.
A man attacked during the incident is in stable condition.
More than 35,000 are expected to take part in the vote.
IEBC Returning Officer Vincent Saitabau said the commission has taken action over complaints raised by some voters and candidates regarding claims of voter bribery and violence.
Six cases have been reported to the Director of Criminal Investigations.
They include a petition by Omondi asking the commission to disqualify Karan and Ochieng for allegedly engaging in voter bribery and violence.
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