Indian authorities say they do not know who is behind the attacks.
In connection with the bomb blast, the Indian Home Secretary, G. K. Pillai referred to David Headley, a Pakistani-American businessman based in Chicago and accused of involvement with terrorism. News organizations have reported that Headley had visited Pune in July 2008 and March 2009 to scout the area near the blast and described him as a suspected member of Lashkar-e-Taiba, one of the largest and most active South Asian Islamist terrorist organisations.

Speculation in India has mentioned both the Lashkar-e-Taiba and the Indian Mujahideen.

The attack occurred just a few days after an agreement between India and Pakistan to resume dialogue at a meet on February 25 in New Delhi. Within the first few hours of the attack the Indian media had already started speculating the attack was aimed as a blow to such talks. "Investigators will doubtless establish the identity ... but the timing of the first major act of terrorism since 26/11 strongly indicates a likely motive: to ensure the forthcoming dialogue between India and Pakistan is sabotaged even before it has a chance to get off the ground."

Repercussions
Location and time
Investigation
Hypotheses about the perpetrators and motives