Former Nairobi Governor Mike Sonko, Mombasa county boss Hassan Joho and Mvita MP Abdulswamad Nassir were Tuesday involved in an altercation at the Tudor Village Hall polling station.
It took the intervention of the police to defuse the situation after the three politicians who were monitoring voting clashed.
Mr Joho was at the polling station with other Azimio la Umoja leaders when Mr Sonko, who had earlier helped secure the release of United Democratic Alliance (UDA) Mvita candidate Omar Shallo from Makupa Police station, arrived.
The two groups engaged in a war of words before their supporters exchanged blows forcing police to intervene.
At some point, shots rent the air. Mr Joho and Mr Nassir escorted Mr Sonko out of the polling station amid gunshots. It was not clear if it was the police or politicians' bodyguards who fired in the air.
Earlier at the same polling station, Mr Shallo and Tudor ward MCA candidate Samir Bhalo were arrested over chaos following claims of vote fraud.
Independent, Electoral and Boundaries Commission (IEBC) Mombasa Returning Officer Swalha Yusuf said voters were generally peaceful during voting and accused the politicians of stoking violence.
She said the polling station was of interest to the candidates due to the high number of voters registered there.
“We want them to maintain peace,” she said.
Police are currently investigating the incident.