Attur Judicial Magistrate Malarmathi also imposed a total fine of Rs 85,000 on the accused in connection with the explosion on September 17, 2002 that also left 31 people injured and damaged 15 houses in the vicinity.
The magistrate sentenced the six accused under IPC section 304 (culpable homicide not amounting to murder) and under Explosives Act.
She, however, acquitted five accused of the charges.
A totasl of 15 persons were arraigned as accused in the case but four of them, including the owner of the illegal cracker unit, died during the pendency of the trial.
Under the impact of the explosion, fifteen houses in the vicinity had suffered damages.