Angry residents at a polling station in Tharaka Nithi County paralysed voting, insisting that it would only resume once missing election materials were provided.
The protest delayed voting at the Mubukuro Primary School polling centre in Chuka/Igambang'ombe constituency until 4.20pm, with electoral agency officials saying ballot papers for the Senate seat were missing.
Independent Electoral and Boundaries Commission (IEBC) county returning officer Mohammed Raka said there was a mix-up of the papers during packaging.
"The ballot papers had been wrongly labelled and that is why they were taken to Tharaka constituency instead of Chuka/Igambang'ombe constituency," Mr Raka said.
He apologised for the inconvenience and said the lost time would be compensated for to ensure that all voters cast their ballots.
He said security and lighting will be assured at the polling centre throughout voting.
Mr Raka noted that similar mix-ups had been reported across the county but were rectified and voting continued.
He added that voting did not start at the right time in Tharaka constituency because of misunderstandings but it later kicked off and was running smoothly.
"Though we have some challenges, voting is going on in all polling stations and we hope it will end well," he said.
But he said polling rooms were congested because there were several independent candidates, making it harder for presiding officers to control crowding.
Tharaka Nithi Governor Muthomi Njuki, who is seeking re-election under the United Democratic Alliance (UDA), and his Jubilee counterpart, Prof Erastus Njoka, also urged the IEBC to extend voting hours so as to make up for lost time, especially in Tharaka constituency.