Several legislators sustained head injuries and bruises in the confrontation.
The locals have threated to force their MCAs out of office for their physical brawl that tarnished their county's image nationally.
The angered residents vowed to teach their MCAs a lesson by impeaching or marching to the county assembly to force its closure until they ended their "intolerable actions".
They complained that their MCAs were focused on fighting for their own positions and amassing wealth instead of serving their constituents.
“We regret voting in such greedy people. We are now seeing their true colours. All they are demanding is hefty allowances,” Lukas Kiragu one of the locals said in Gatanga.
The meeting in Kiambu had been called turned ugly after two rival factions in the county assembly clashed over a plot to change the county leadership.
The two rival groups traded spats outside the hotel which escalated into a fistfight, forcing the conveners to instruct youths who were in the venue to eject their opponents on grounds that they were intending to disrupt the meeting.
Gatanga Ward MCA Nahashon Gachuhi suffered head injuries and bruises on the body after he was hit with a stone and roughed up by the youths while his Kamachari counterpart got serious bruises on his back, face and abdomen.
Murang’a Jubilee Party Deputy Secretary-General Charles Njoroge, who is also the Kigumo Constituency party chairman was injured on his lower jaw and got bruises following beatings from the youths who escorted them out of the hotel.
The victims reported the matter at the neighbouring Runda Police Station and later sought treatment at the Aga Khan Hospital in Nairobi.