Five gangsters, who were on the lookout for two siblings to avenge their associate's killing, hurled a country bomb at their parents' house and when the couple ran out, hacked them to death, the police said Monday.
Since the sons could not be found, the gang attacked their parents as they were running out of their house, they added.
The woman was hacked to death outside the house while her fleeing husband was killed by the gang 100 metres from the residence which was destroyed in the blast, police said.
The siblings were both on bail in connection with the case and and were working in Coimbatore. They had come home on Sunday.
A special team has been formed to trace the gang.