Tension prevailed in Pasumpon village in the district on Wednesday after some persons threw 'wet red sand balls' at a convoy of Tamil Nadu ministers and stones at DMK activists near the memorial of freedom fighter Pasumpon Muthuramalinga Thevar.
Police said seven DMK functionaries were injured in the stone pelting and they had been rushed to a government hospital. Six of their cars suffered damage with windscreen and windows broken.
The incident happened hours before DMK leader MK Stalin was to visit the memorial at Pasumpon village.
Police said ministers Sellur K Raju, R Vaidhyalingam and Kamaraj were returning after paying homage at the memorial on the occasion of Muthuramalinga Thevar's 106th birthday.
Vaidhyalingam's shirt was stained with red soil as he had rolled down the window of his car to greet the people. He was not injured, police said.
The ministers, while returning, wanted to have a look at the 'Annadhanam' (feast) being given to the people near the memorial, when some slogan shouting miscreants hurled the wet red sand balls at them, police said.
Some hurled stones at the cars of AIADMK MLA Murugan and Kadaladi AIADMK Union Chairman Padmanabhan, sources said.
Police said the ministers then got back into their cars and left the place.
Police said miscreants shouted slogans against the government for imposing prohibitory orders for the celebrations.
The miscreants would be identified using video footage and arrested soon, police said.
Meanwhile, MDMK leader Vaiko, who paid homage at the memorial, condemned the attack.