Timer devices were used to trigger blasts in Bengaluru-Guwahati express

Chennai: Various police units, including NIA, CB-CID, city police, special division, railway police, RPF have despatched their representatives and were together trying to solve the terror puzzle by chipping in with their inputs after the twin blast rocked Central station around 7.13 am on Thursday after the train arrived late by one-and-a-half hours.

The initial round of enquiries showed that the perpetrators of the crime had used an improvised explosive device with a timer to create panic at the railway station. “Forensic teams have collected ball bearing and pellets besides traces of ammonium nitrate, nitro toluene and sulphur from the scene of blast,” sources said.

The police are not sure if the bags containing the explosive arrived on the train or somebody planted the bombs in the two compartments after the train arrived at platform No. 9 at Chennai Central. One strong possibility is to trigger the blast using a timer. “They could have set the time in the bomb and kept the bags with explosives in S4 and S5 compartments,” said an official.

It is also possible that the suspects planted the bombs and then triggered it using a remote or mobile phone. “If they were using a mobile phone trigger, it can be used from anywhere, but if they were using remote control, they could have been somewhere nearby,” police sources said.