United Democratic Alliance candidate in the Kiamokama by-election in Kisii - Nyandusi Nyakeramba - was set free on Thursday afternoon after hours under arrest.
He said he was taken for a "round trip' in a police van before he was later released at Ogembo town in Bomachoge Chache.
"They only took me round telling me nothing in particular. They did not even tell me the reason they were holding me," said Nyandusi on the phone.
Also released alongside him are politicians Zaheer Chanda (Nyaribari Chache) and Don Bosco (Kitutu Chache North).
They were also seized in Kiamokama on Thursday morning as voting begun.
Nyandusi was picked from outside his house at Moremani area and bundled into a police truck while Chanda and Bosco were picked from Emeroka area.
A press aide in the office of Kisii Deputy Governor Joash Maangi was however re-arrested and locked at Ogembo Police Station in Bomachoge Borabu.
Police are yet to give reasons for his detention.
Separately, Kenya National Congress party officials spoke of "police intimidation" as voting got underway across the Ward.
Party Secretary General Benjamin Gisore said a party agent and a supporter of their candidate Dominic Atenga were arrested.
The agent identified as Elton Omosa was picked by police from Moremani on Thursday morning.
Meanwhile, Masaba South Sub-County Police Commander Mark Bitok said they have intensified surveillance to Ward off hooliganism.
He especially said they are discouraging voters regrouping outside polling centres after casting votes.
