Mumbai:
A day after the deadly Mumbai blasts that killed 17 people and injured 131, intelligence sources have said that the close circuit television (CCTV) footage from Opera House, one of the blasts site, may yield some clue.
Sources have told NDTV that on the CCTV footage, three or four people were seen talking on the phone for over an hour and a half at the same spot. These sources point to the likelihood of sleeper cells of Indian Mujahideen (IM) being activated.
The three bombs that shook Mumbai on Wednesday were Improvised Explosive Devices (IEDs), prepared with a deadly mixture of ammonium nitrate, Tri-Nitro Toluene (TNT) and fuel oil.
Ball bearings were used as shrapnel and smart cellphones as timers.
"Ammonium nitrate was used. The fact that blasts took place within minutes of each other shows it was a coordinated terror attack," said Union Home Minister P Chidambaram.
In two of the three bombs, over a kilo of explosives were used. Also, the group behind the strike is smaller than usual and did not communicate on phones or emails - a new strategy to avoid being tracked.
The use of IEDs also hints at a possible IM involvement. The IEDs are their signature explosives. But what fuels the theory is that this blast almost coincides with the fifth anniversary of the 2006 Mumbai train blasts, now linked to the terror group.
Sources also tell NDTV that remnants of the Students Islamic Movement of India (SIMI) and fringe elements of IM are under the scanner.
Investigators are in touch with the Uttar Pradesh and Karnataka Police - hubs of these groups.
However, preliminary evidence raise questions on IM's involvement, most important being the fact that none of the bombs were expertly planted to maximise the impact.
In Zaveri Bazaar, the bomb was wrapped in an umbrella and kept face-up on a scooter. The result: The impact was felt upwards and not on the ground.
In Dadar, the bomb was placed on a transformer box next to a tree that bore the maximum brunt.
And at Opera House, the bomb was kept at a 60 degree angle instead of a 30 degree angle that would have maximised impact.
The government, meanwhile, says that they are not ruling out anything.
"We are not in a position to say this group or that group and all aspects will be probed," Home Minister P Chidambaram said.