THRISSUR: The National Investigation Agency (NIA) will investigate the 1997 Chennai-Alappuzha Express train bomb blast in Thrissur. The incident in which four people were killed was investigated by a special team of the Kerala Police, but even after 26 years, none of the accused was caught. The mastermind was identified as Ayub alias Ashraf from Thrissur Mullassery. The NIA also sought information on this case after receiving information that a module of ISIS had been formed in Thrissur recently.

The blast took place on December 6, 1997, at 7:30 a.m. when the train was leaving Thrissur station. A leaflet found at the scene suggested that the blast was carried out by the 'Islamic Defense Force'.

The Central Intelligence agencies had assessed that Islamic fundamentalist groups operating in Tamil Nadu and Kerala were behind the blasts. On the same day, seven people were killed in blasts in Tiruchirappalli and Erode in Tamil Nadu. Similar pamphlets were also found. Although the accused in those cases were arrested later, the Thrissur blast case did not go anywhere.