A police team intercepted Prabhu and Bharathi at Kaalpirivu village near Manamadurai, 15-km from where they escaped earlier while being taken to a court in Sivaganga district from the Central prison here.
The duo attempted to attack the police personnel and police opened fire in self-defence, killing them on the spot, they said.
Prabhu and Bharathi had given police the slip when the police escort team stopped the vehicle in which they were being taken after they complained of chest pain. They attacked two policemen and fled.
The injured policemen were admitted to hospital.
Police registered a case and launched a hunt for them.
Twenty six-year old police sub-inspector Allwyn Sudan was stabbed to death in Sivaganga district by a group of youths on October 27 when he asked them to take an alternative route while they were on their way to attend the death anniversary of the Maruthupandiyar brothers.