According to reports, at least one person was injured as a crude bomb exploded in Patna railway station earlier in the day.
It was the first blast that rocked the city on Sunday.
Other blasts occurred around Patna's Gandhi Maidan where over 25,000 people have already gathered to attend Modi's rally, reports said.
The police have detained one person so far.
Meanwhile, Modi has arrived in Patna and is expected to address the rally soon.
Earlier, reacting to the explosion, Congress general secretary Digvijaya Singh tweeted: " What a coincidence blast at Patna Railway on the day of Modi's Rally ! Challenge to Nitish Govt to find the culprit !"
--IBNS (Posted on 27-10-2013)