The bomb, planted in a two-wheeler, exploded at 9 am at a crowded bus terminal, barely one km away from the police headquarters, official sources said.
The Assam Rifles personnel were patrolling the area.
The injured have been shifted to a nearby hospital where the condition of one of them was stated to be serious, sources said.
Top police officials rushed to the area. Preliminary reports said the blast could have been triggered by an IED and investigations were on.