One Natarajan, who allegedly hurled the bombs, was arrested with the help of a telephone lineman who managed to catch hold of him, police said.
The lineman also suffered splinter injuries.
The accused Muthupandi (ed correct), who was arrested in connection with the murder of Pasupathi Pandiyan, founder of the Devendrakula Vellalar Kootamaippu, about two years ago, was on his way to the Dindigul District court to attend the hearing,when he was attacked.
Muthupandi, who is a councillor of the Dindigul Panchayat Union and a member of Tamil Nadu Makkal Munnetra Kazhagam, was also allegedly involved in the murder of Natarajan's father, sources said.