Patna/New Delhi: There were two Indian Mujahideen human bombers getting ready in Patna on Sunday morning to target BJP leader Narendra Modi and others, but their carefully laid plan collapsed due to a mistake in changing timer battery, say investigators.

NIA and local police sources said, the plan was on the lines of May 21, 1991 attack in Sriperumbudur in which an LTTE human bomber blew herself up killing Rajiv Gandhi.