Indian Jihad motive supplied in this [1] Hindustan Times piece, "Terror revisits Mumbai as 147 die in serial blasts" :

Terror had a plan in mind as it visited Mumbai on Tuesday. The powerful explosions that killed at least 147 rush-hour commuters and tore apart seven local-train compartments were methodically executed to shock the country’s financial capital and hurl it into chaos.

Unlike the 1993 blasts, aimed at the city’s institutions, 11/7 was meant to hit the people who represented the face of globalising Mumbai.

The bombs — in all probability improvised explosive devices, the choice of terror groups in the past 10 years — exploded mostly in first-class compartments ferrying professionals and businessmen during the evening rush hour.

Terror in Mumbai

The first bomb exploded at 6.15 p.m. at Bandra station, followed by one on a train pulling out of Mahim station.

All the stations hit (Matunga, Mahim, Bandra, Khar, Jogeshwari, Borivali and Mira Road) are strung along a 60-km stretch of the western commuter line. These are among the city’s affluent suburbs — home to bankers, businessmen, entertainment moguls, actors and other upper-middle-class professionals.

Mumbai Police Commissioner A.N. Roy said investigations were on to zero in on the terrorist outfit responsible. Preliminary reports suggest the involvement of the Lashkar-e-Tayebba. The police are probing possible links between the blasts and the seizures of radio-enabled detonators in Mumbai in March and a huge consignment of RDX in Aurangabad in May. They had busted two suspected modules of the Lashkar following the seizures.