The masterminds behind the bomb blasts are Rasool Khan Parti and Mohammad Sufiya Ahmed Patangiya - both, currently residing in Karachi (Farahan Arcade Gulistan). They are originally from Hyderabad in Andhra Pradesh.
Both were from Harkat-ul-Jihad-al Islami, but found Students Islamic Movement of India to be the best hiring ground. They were also responsible for murder of Gujarat Minister, Haren Pandya. The planning was obviously done in Kotli, Pakistan in May this year.
So, these blasts will be watershed in the Indian history - as this is the first time that Indian Muslims became the canon fodder instead of the poor Pakistanis and Bangladeshis who end up in the terror camps across the border. All the folks were sent to UAE for "jobs" and from there to Dubai and then to Muzaffarabad in PoK. That is where they were trained. The report says that they avoided the use of RDX as such a large operation could have been detected with the kind of risk involved in bringing RDX to India. The training thus had a new nomenclature - Alternate Explosions! So, RDX was replaced by Ammonia Nitrate.