They said as per initial reports Improvised Explosive Devices (IED) was planted near the office of ruling BJP office in the southern part of the city and the blast material Ammonuium Nitrate had been frequently used by IM in the past.
"It is too early to point a finger at any group but the needle of suspicion goes to IM," sources said.
The blast took place just on the eve of third anniversary of blast in Bangalore's Chinnaswamy Stadium, which too is suspected to have been carried out by IM.
Besides, in the nearby temple, there were many devotees yesterday being the Tuesday, considered to be auspicious especially during ongoing 'Navaratra' period.
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"Since the BJP ticket distribution is over and today being Wednesday, there is less crowd in the place, thus avoiding a major tragedy. But we are sure that the spot was chosen carefully," a source said.
The Home Ministry has already sent a team of NIA and a bomb disposal squad of NSG had been sent to Bangalore to help the local police in post-blast investigation.
Meanwhile, Home Minister Sushilkumar Shinde is likely to travel to Bangalore tomorrow to visit the site as well meet those who were injured.