First of all i will say that those who did these acts are enemies of all not of particular country or religion and secondly it is not easy to say that this has been done by which organisation bcaz the modulas operandi of all such organistaion through out the world is same i.e, soft targets at busy places. so we cannot rule out the hands of various organistions other than Islamic organisations to do such a cowardly acts of killing innocent people. In my view this whole thing should be investigated by some central agency and one thing more that is they i.e, the central agency, should not say that those involved were killed in some encounter some where in the country by killing some body innocent or some unknown after some days, which is generally done after such incidents which all of us know.