Three bombs were hurled at the shop owned by one Nizzar, a former convict, by some two-wheeler-borne persons.
Nizzar was also attacked by them using lethal weapons, police said.
Nizzar, a worker of Social Democratic Party of India, sustained serious injuries in the incident and was admitted to a private hospital here while the other two others at the Kozhikode Medical College Hospital, police said.
Nizzar was an accused in the murder of Binu, a CPI(M) worker in 2001. After his release in the case, he was running the shop in Kuttiyadi, police said.