One theory went that the explosives were put on the train which was on its way to Guwahati in Assam through the Seemandhra region and the blasts occurred in Chennai as the train was delayed by a few hours.
BJP spokesperson Nirmala Sitaraman said during a television debate on Thursday that her party wasn't just speculating that the attack was meant for Modi. She said the BJP had raised the issue of Modi's security with the home ministry in the past as well, based on reports in the media that there is a threat to the BJP's prime ministerial candidate.
The BJP said it was concerned with the security of its PM candidate
Last year on October 27, a similar bomb attack took place in Patna where the BJP's PM nominee addressed a massive rally. In fact, a series of blasts took place in the Bihar capital on that day, killing six persons. Security and media observers have found a similarity of the blasts in Chennai and Patna.
Sitharaman said the government should always keep the security arrangements alert.
Last month, four persons were held in Rajasthan for they were reportedly planning an attack on Modi.