Former Rarieda MP Nicholas Gumbo protested an attack on his convoy during an Azimio rally in Bondo at the weekend.
Mr Gumbo, who is eyeing the Siaya governor seat on a UDM ticket, was barred from accessing Raila by rowdy youths who pelted his motorcade with stones.
Several vehicles were destroyed in the process as Gumbo and his running mate David Ohito sought to access Bondo Primary School where the rally presided over by presidential flagbearer Raila Odinga was taking place.
According to Mr Ohito, their vehicles were pelted with stones and three of their supporters sustained head injuries.
Ohito, who condemned the Saturday incident, said they were aware of those behind the violence.