The occupants belonging to the Thevar community were returning after attending the 105th birth anniversary celebrations of freedom fighter and Thevar community icon Pasumpon Muthuramalinga Thevar when they were attacked late last night.
The assailants, hiding behind some bushes, hurled three petrol bombs which exploded and the car caught fire.
Three persons suffered serious burns, police said. The injured have been hospitalised.
Police have been deployed at the government hospital where some of the injured have been admitted.
The car has been seized.