As the news spread, members of a community killed a 47-year-old labourer who was on his way to work. Enraged by this, two persons were fatally attacked in retaliation by members of the other community, police said adding the victims were aged 12 and 25.
The police resorted to lathicharge and lobbed teargas shells to disperse the clashing mobs.
Even as the city was gripped by tension, a group of people brought the body of the 12-year-old boy to the Udayagiri police station alleging he was killed in police firing.
Police, however, disputed this saying the victim was stabbed to death.
As the crowd refused to accept their version, the police agreed to their demand for a post mortem by a three-member team of doctors to ascertain the cause of death.
Deputy Commissioner P Manivannan and City Police Commissioner Sunil Agarwal visited the violence-hit areas where shops and business establishments were closed.
As a precautionary measure, prohibitory orders under Section 144 Cr.PC were clamped.
In Bangalore, Home Minister V S Acharya told reporters that central security forces stationed in Coimbatore had been summoned to Mysore where the situation was tense.
Besides resorting to lathi-charge and bursting of teargas shells, police used rubber bullets to disperse the crowd, Acharya said.
Police have made tight security arrangements and the situation is "seemingly peaceful", Acharya said. The Minister blamed "difference of opinion" for the clashes.