The seat fell vacant when the divisional commissioner took action against corporator Shakila Qureshi and disqualified her after she kept aloof from the mayoral polls in 2012.
The mob was furious, since the ticket went to the wife of one Ramesh Patil of the NCP, while the seat was held by the Congress, sources said.
The Mumbra police, which dispersed the mob, took two people into custody, who have been identified as Iliyas Satpute and Ahmed Hussain, sources said.