Tamil Nadu Chief Minister J Jayalalithaa said the victims were injured when some anti-social elements hurled petrol filled bottles at their van while they were returning after paying homage to veteran freedom fighter and Thevar community icon Pasumpon Muthuramalinga Thevar in Ramanathapuram district on October 30.
While Jayapandi died on November 3, Sundarapandi and Vetrivel succumbed the next day in a hospital, she said in a statement while condoling the deaths.
The Chief Minister said she had directed a payment of Rs five lakh each as relief to the families of the victims.
Earlier, three persons had been killed in various incidents on October 30. Jayalalithaa had informed the state Assembly that adequate security measures had been put in place and peace restored in the district.