However, it did not explode and was recovered by the Bihar Police only after a day.
Among those arrested by NIA included Hyder Ali alias ‘Black Beauty', Mojibullah, Numan Ansari and a juvenile (whose identity was not disclosed), he said.
Except for Ali, NIA had announced a cash reward of Rs five lakh on other three who allegedly planted the bombs during October 27 rally of Modi.
At least seven people were killed and scores others injured when bombs exploded at a make-shift railway platform and at the rally of Modi.
Kumar said with these arrests NIA has cracked three cases which include the Bodh Gaya temple blasts, the Patna rally blasts and explosions in Hyderabad's Dilsukhnagar.