Security agencies probing Thursday's twin explosions inside Bangalore-Guwahati Express here have found some similarities with Patna blasts last year in which cadres of banned Indian Mujahideen (IM) terror outfit have been arrested.
Sources privy to the probe today said the trigger mechanism for the blasts was almost similar to that of Patna explosions last October that rocked the political rally of BJP's Prime Ministerial candidate Narendra Modi, leaving five people dead and 20 injured.
The sources said that it was difficult to pinpoint the group behind the attacks but there was a suspicion that some people having association with the banned SIMI may have been involved.
After release of the video footage by the CB-CID of Tamil Nadu police, central security agencies were now focusing on questioning the recently arrested IM operatives including Yaseen Bhatkal and Akhthar, the sources said.
Bhatkal and Akhther have been active in Bangalore and had also set up several safe houses in and around the city, the sources said.
The explosive devices fitted with carbon-zinc battery were assembled with a quartz time piece inside a bag which was placed in S-4 and S-5 coaches of Bangalore-Guwahati Express, the sources said, adding it was placed in a hurry due to which the explosive material did not have the proper impact.
A 24-year old woman was killed and 14 people were injured when the two bombs went off inside the train at the busy Central Railway station here on Thursday morning.